The Galaxy Watch 4's looks are familiar: one version, the Galaxy Watch 4 (left) resembles the first Galaxy Watch Active. The Galaxy Watch 4 Classic (right) looks more like the Galaxy Watch 3.
The watches have the same functions, but the Watch 4 is less expensive (starting at $250) and has an aluminum case, while the Watch 4 Classic (starting at $350) is stainless steel and has a physical rotating bezel.
The Galaxy Watch 4 gets a few more color options: the 40mm version comes in black, silver and pink gold, while the 44mm version comes in black, silver and green. The Watch 4 Classic only comes in silver and black.
Both watches have circular touch controls: the Classic uses the rotating bezel, while the Watch 4 (non-Classic) has a touch-sensitive rim.
The watches have higher-resolution Super AMOLED displays, faster processors, more RAM, 16GB of storage and can fast-charge to 10 hours of battery in 30 minutes.
The watches use Google Play for apps, but have Samsung Health and a variety of Samsung watch faces. They're the first examples of Google's new WearOS 3.
The watches promise to sync more seamlessly with Android phones, but there are no plans for iOS compatibility.
The health tech onboard includes some new features: snore detection (when using a nearby paired phone's microphone when sleeping) and a new body analysis sensor using electrical impedance.
Third-party apps will be able to work with Samsung's fitness ecosystem, including Strava and Calm. Spotify is supported, too.
A new sensor array on the back of the watch combines ECG (electrocardiogram), optical heart rate and electrical impedance. It's called the Samsung BioActive Sensor.
Keep scrolling for more photos of the Samsung Galaxy Watch 4 and Samsung Galaxy Watch 4 Classic.