Editors' note, November 10, 2014: This article was original published on August 13, 2014. It has been updated to include details about Android Lollipop.
Put almost any two Android smartphones from different brands next to each other, and you can easily notice they don't look alike. I'm not just talking about the obvious external design features; turn on the screens and you'll see that each operating system has its own style too.
What you're seeing is a custom "skin" that original equipment manufacturers (OEMs) create to run on top of the Android operating system. This skin alters many aspects of the phone's user interface (UI), from the menu design to the home screen shortcuts.
Each of the top OEMs -- HTC, Samsung, Sony, LG and Motorola -- creates its own UIs for the Android phones they build, aiming to give customers a special experience, and the open nature of Android allows and even encourages them to do so.
That said, each Android skin has its fans while some users prefer to avoid them completely for the stock UI. So, to help you find the best skin for you, I'm going to tell you all you need to know about each UI, and point out the best and worst of each.
Stock Android, also called "pure Android" or "vanilla Android," is the unaltered operating system created by Google. Android's design has evolved significantly through the years, from version 1.0 on the HTC T-Mobile G1 to Lollipop today. Today, Google's Material Design gives Android Lollipop its distinct look. You'll also still find the Holo (short for Holographic) UI on many Android devices, running 4.0 and newer. Holo first appeared on the tablet-only Android 3.0 Honeycomb and later landed on phones with Android 4.0 Ice Cream Sandwich.
Defining design traits
The most defining characteristic of Material is its bright, colorful design -- the app drawer, notification shade, and settings menu have either white or transparent backgrounds with color icons. Nearly everything about Material is meant to be sleek, yet playful from the subtle animations with you unlock the screen, open the app drawer and unveil the notification shade. There are also bright colors throughout the UI; in the settings menu, in the app icons and in many preinstalled applications.
Transparency is a big theme in Material, with a transparent menu bar, lock screen and notification shade. There's plenty of white space, too, which makes text look more prominent.
Stock Android can vary between devices, depending on the version of the operating system. Older flavors, especially Jelly Bean and KitKat, use the Holo UI. Newer phones, that are either currently or soon to be running Lollipop, feature Material Design.
The most prominent feature in stock Android is Google Search. There's a persistent Google search bar at the top of each home screen that you can't easily remove and you can swipe up from the bottom of any screen to launch Google Now.
That's really it, since the point of stock Android is to not clutter the phone with too many features. It's up to you to add the extras you want by downloading apps, or adding widgets to your home screen.
What you need to know: Stock Android is the top choice among Android devotees because it gives them exactly what Google created. The design is uncluttered, and all of the latest features that Google unveils with new versions of Android usually work just as advertised. Also, devices that ship with stock Android, such as the Nexus phones and tablets, more often than not are the among the first to get upgrades to the latest versions.
One of the most distinguishable UIs, Samsung TouchWiz has matured a bit over the years, but it's still one of the brightest and most cartoon-like designs out there. The interface dates back to 2010 with the release of the Samsung Galaxy S. Today the Galaxy S5 ships with TouchWiz Nature UX version 3.0.
Defining design features
TouchWiz is best known for its bright colors, whimsical animations, and a feature-rich design. There are elements of KitKat scattered through the UI, including the transparent app drawer and status bar, but Samsung hasn't hesitated to make its mark.
Icons are large, so they're easy to see and press. They've gotten flatter in the latest iteration, but they still have a bit of a skeuomorphic look (designed to look like real-world items). The notification shade on the Galaxy S5 has a blue heading and navy background, with a row of settings shortcuts at the top that you can customize. That blue accent color also pops up in the pre-installed Samsung apps, such as the phone dialer and the photo gallery.
A big part of TouchWiz is that you can't customize the design or color scheme; you get to pick your wallpaper and change the font, but that's about it. Samsung does this partly to help make the phone easy to use for everyone, from Android veterans to first-time smartphone buyers.
Continuing the theme of simplicity, many of the extras you get with TouchWiz are meant to make the phone easier to use. First up is the aptly named Easy Mode, which puts extra-large icons and widgets on the home screen, simplifies the settings menu so you only see the most common options, and gives you an entire page for your favorite contacts.
Multi Window is a feature that lets you view two apps at once, stacked on top of each other, so you can check out a webpage in one window and text your friend in the other. There's also Toolbox, a small circle that floats over most of your screens with shortcuts to any app on your phone. You tap it to open a tray of apps, and when you're done, the circle becomes transparent so it almost disappears.
What you need to know: With its bright and simple layout, Samsung TouchWiz is one of the easiest UIs to use and it's great for anyone who's just getting started with a smartphone. Part of why that's true is that Samsung sprinkles helpful features throughout that give you quick access to the apps and information you want. However, the bright and restricted design is polarizing -- some like it, others loathe it. Also, Samsung's tendency to pack so many features into its phones can be overwhelming.
HTC Sense has been around for several years, dating back to 2009 with the release of the HTC Hero, also marketed as the T-Mobile G2. Today we're up to version 6.0, which debuted with the HTC One M8. Thanks to updates from HTC, Sense 6 has also made its way to older phone models, including the One (M7), One Max, and One Mini.
Defining design features
Sense is centered around a sleek and elegant design, which keeps the home screen and menus tidy. You get a little bit of control over the design, as you can pick your own system font and choose the color scheme for your phone. There are from four brightly colored themes and a black and white option.
The color themes are used to determine the accent colors throughout the operating system and they also affect the appearance of HTC's apps, including Messages, Calendar, FM Radio, Gallery, Email and TV.
The notification shade is very much like stock Android -- simple, black, and has two panels. You swipe with one finger for your list of notifications, or swipe with two fingers for a grid of quick settings which you can customize. One thing that sets Sense apart from other UIs is the app drawer. It has pages that scroll vertically, and you can adjust how many apps appear on each page.
Sense is best known for Blinkfeed, a custom feed of updates from Facebook, Twitter, Google+, Fitbit, Foursquare, and Instagram that takes up one of your home screens. You can even make it your default home screen if you choose. To view it, you swipe all the way to the right. You can change the color of Blinkfeed by picking different themes for your phone.
Though they blur the lines between software and hardware, the Motion launch gestures are another key part of Sense. Using them you can do simple tasks with your phone by picking it, and tapping or swiping on the screen. For example, when the screen is off, tap it twice to wake it, with another you pick up your phone and swipe right to launch Blinkfeed.
What you need to know: HTC Sense is the most social UIs of this bunch, and I appreciate that it gives you some freedom to personalize your device. With Blinkfeed, all of your social updates are organized into a pretty menu, but if you don't want to use it, you can easily turn it off. While Sense doesn't offer as many customization options as other UIs on this list, I don't really miss them, because the design doesn't get in the way.
Example device: LG G3
The history of LG's user interfaces is a bit murkier than other UIs, since LG tended to use stock Android in its early smartphones. The first version of the company's custom UI popped up on the 2012 Optimus Vu.
LG developed its UI design, which has no official name, over the last few years with the 2012 Optimus G and the LG G2 from 2013. In 2014, LG completely revamped its UI with the G3. I'll be using that phone as my primary example here.
Defining design features
LG's interface has a modern, flat design, yet icons for LG's apps have shadows that make them look somewhat 3D. Still, there are no rounded corners and few realistic-looking effects. The color palette is muted, which adds a bit of sophistication, especially when compared to TouchWiz.
Though the color scheme and overall design are a departure from TouchWiz, the two interfaces have very similar layouts. The notification shade has a row of quick settings at the top, followed by your list of notifications. The app drawer has a transparent background, and the same streamlined configuration as TouchWiz.
One feature that sets it apart from TouchWiz is that LG gives you a significant amount of freedom to customize the UI. You can pick the animations you see when you scroll through your home screen panels, as well as when you turn off the screen or unlock the screen. You can change the configuration of, and even hide, the on-screen control buttons -- the back, home, and recent apps buttons at the bottom of the screen. Most phones don't offer those options.
Though LG's interface comes packed with customization options, you can get even more in the LG SmartWorld theme store. There you can download wallpapers, new keyboard designs, ringtones, and complete phone themes, which include icon packs and fonts.
Another software extra is QSlide, which you'll find in the notification shade. It lets you open specific apps (including the browser, calculator, and messages) in a separate window that floats on the screen over anything else you're doing. Using QSlide, you could browse the Web while texting your friends.
LG's UI also has a feature called Dual window, which shows two apps on the screen at the same time, and it's almost identical to TouchWiz's Multi Window option. Lastly, smartphone novices can turn on EasyHome. This transforms the home screen into a nearly full-screen phone dialer with shortcuts to messages, camera and contacts. Easy Mode also makes the menus, text and icons much larger so they're easy to read.
What you need to know: If you like the on-screen features of Samsung Touchwiz, but want a more subdued design, LG's interface is a great choice. The multi-tasking features are helpful if you spend a lot of time on your phone, and the optional simplified home screen is good for first-time smartphone buyers. The customization options can be a bit daunting, just because there are so many, but that means you get plenty of freedom to personalize your phone.
Example device: Motorola Moto X
Though Motorola used to call its software design MotoBlur, it dropped that brand a few years ago, and now focuses on using stock Android on its devices. Even when the company was using the name MotoBlur, Motorola didn't make too modifications to Android, especially in phones from the last two years. The UI usually just added a "Circles" settings widget and a few custom app icons.
Defining design features
Motorola's design philosophy is to take stock Android and add just a few of its own features, while still preserving the basics of the operating system. It's unsurprising then that Motorola phones, notable the last generation Moto and Droid lines, look almost identical to stock Android.
Those phones use the Holo UI, and all of the familiar elements are there, including the transparent status bar, app drawer with tabs for apps and widgets, and a black theme throughout.
First, you get Touchless Control, an always-on Google Now voice assistant. Even if your phone is locked and the screen is off, you can say "OK, Google" followed by a command to do a Web search, get directions, or call home. It's a particularly great feature for when you're driving or any other situation where you can't touch the screen.
Next is Active Display, which shows notifications on your lock screen for emails, phone calls, messages and more. All you need to do lift your phone to turn on the display, and you can tell at a glance if there are any new notifications. You can even get a preview of the notification by swiping up.
Another neat feature is sending and receiving text messages from the Chrome browser on your computer using Motorola Connect. There are several third-party apps that can do this, but it's nice that it's already built in.
What you need to know: Motorola's UI takes the best of Android and adds to it. Not only do you get the familiar stock experience, but you also get a handful of extras, such as Active Display and Touchless Control, which improve on Android's already solid voice search and notification features. Because of the UI, Motorola phones are a good choice for Android purists who aren't interested in a Nexus device.
Sony Xperia Home
Example device: Sony Xperia Z2
The Sony Xperia Home user experience dates back to the beginning of the Sony (not Sony Ericsson) Xperia lineup, which started in 2012. The design hasn't changed too dramatically since then, though the KitKit user interface on the latest Sony Xperia Z2 is a bit more modern.
Defining design features
Sony Xperia Home is one of the few UIs that's still holding on to the 3D look that was popular in earlier versions of Android. Many of the icons for pre-installed apps, including Album (photo gallery) and Movies look like candies, with bright colors, rounded edges, and a design that pops off the screen. Likewise, in the settings menu, there's a realistic raised design, with toggles for Bluetooth and Wi-Fi that look like physical switches. That means the Xperia UI looks a bit dated compared to other phones, but it's still easy on the eyes.
Xperia Home includes several colorful responsive themes with wallpapers that move as you swipe your finger. You can also download extra themes which drastically change the interface. One such theme gives your phone a nautical wood effect, complete with compass icon for the home button.
Sony includes a few neat features with its UI. First is Small apps, a floating app window that hangs out on your screen so you can do something else at the same time. It's looks and works just like LG's QSlide.
There's also Simple Home, Sony's version of TouchWiz's EasyMode, or LG's Easy Home. It gives you a paired-down home screen with a large grid of apps and shortcuts to helpful tools, such as speed-dial numbers and settings.
What you need to know: Though Sony's Xperia UI design still relies on 3D effects and an older Android style, it still looks contemporary for now. The clean look keeps things simple, but it's not as sophisticated or exciting as others on this list. Really, you're more likely to pick a Sony Xperia smartphone for its sleek hardware than its forgettable software.
Android Lollipop ushered in a brand-new design for Android, with a cleaner, modern look. It's up to the top OEMs to decide how they'll integrate Material Design into their skins, either with sweeping changes or smaller tweaks.
While Samsung, LG, HTC, Motorola and Sony want to keep their phone designs current and fresh, they also rely on custom UIs to distinguish their devices. Whether you love them or hate them, don't expect these custom UIs to disappear any time soon.