If you're using the camera in automatic "Photo" mode the results should look exactly the same because both phones use the same 12 megapixel wide-angle lens in this mode.
This sunset shot looks great on both phones: The colors in the sky look vibrant, while the city on the bottom looks sharp despite the challenging light. Apple added a Smart HDR feature in the XR, XS and XS Max phones that brings out more highlight and shadow detail in photos.
Both the iPhone XR and iPhone XS have the same 7-megapixel TrueDepth camera system that can perceive depth and create a blurred background or a portrait mode effect on selfies.
The iPhone XS uses that second, telephoto lens as an optical 2x zoom and then switches to digital zoom beyond that. The iPhone XR uses digital zoom exclusively.
Photos and videos at the same magnification will look sharper on the iPhone XS than on the iPhone XR which relies on software exclusively to achieve a closer shot. In this shot of the lanterns at 5x, you'll notice the one on the right looks shaper with better detail on the gold strings at the bottom.
And the XS can get even closer to the shot. It can go up to 10x by using a combination of optical and digital zoom as seen in this shot.
Both phones struggle with zoom in low light, but in this side by side shot you can see how much closer the XS is capable of getting when compared to the maximum 5x zoom on the XR.
The iPhone XR uses he wide-angle lens for portrait mode, while the XS uses that second telephoto lens which comes in closer to the subject.
The iPhone XR only has one wide-angle lens, which means its relying on software alone to separate the background and foreground. Edges around the hairline of the subjects look a bit more abrupt, but the subjects look sharper than on the XS.
The iPhone XS uses the second telephoto lens to capture the subject. It uses information from both the wide-angle and telephoto lens, combined with software, to discern what to keep in focus and what to blur out in the shot. You'll notice the transition from subject to background looks smoother than on the XR and the image has a softer look.
The XR gives you a lot more space in the frame to work with which can be a plus, but lines along the edges of the frame can start to look warped.
The XS comes in closer, even though it was taken at the same distance as the previous shot, but the edges look even and the shot is well proportioned.
But if you come in for a closer portrait on the XR the wide-angle lens can cause the subject to look distorted. You'll notice his facial features are different dimensions and look unnatural when compared to the previous shot from the XS.
Portrait mode on the iPhone XR didn't activate fast enough to capture the toddler in motion, so only the XS was able to produce the blurred background effect. This happened a lot, and I had to adjust my distance constantly to get it to work on the XR.
If you turn your back to the phone, the XR can't create a blurred background effect.
Portrait mode on the iPhone XS works no matter what direction you're facing. Even when faces are not visible like in this shot.
Portrait mode also wont work on plants...
The XS can handle plants, but the cutout around the petals and stems isn't perfect.
The XR can't figure out what to blur out in this shot.
It takes the XS a few tries to lock in portrait mode on objects, but eventually it pulls it off, as seen in this shot.
In fact, portrait mode on the iPhone XR (on the left) only works on humans. The iPhone XS on the other hand was able to apply the bokeh effect without a hitch in this shot of the dog.
Here's another pet portrait from the XS that the XR wasn't able to get. Apple may add this feature to the XR with a future software update, and you can currently install a third party app that will allow it. But for now you'll get a "no person detected" sign on the camera interface if you try it on anything other that a human face.
The exception to this rule is when there's a person in the shot alongside the pet. When I put my dog next to my toddler in the frame, the iPhone XR was able to capture them both and correctly blur out the background, but it took a lot of adjusting, and a lot of patience.
The iPhone XS was able to capture my subjects in portrait mode almost immediately.
Portrait mode on the iPhone XR really shines in low light. Because it's using the main lens with the wider aperture, it's able to let in more light in dimly lit scenarios. If you can get past the slight distortion.
The proportions in this shot look a lot better, but the subject looks darker and the image shows a lot of noise.
This portrait taken in a dimly lit tiki bar is by no means perfect, but you can at least make out the subject and what's happening in the scene behind him.
The same shot on the XS is barely usable. The subjects face looks dark and the background is murky.
This low light portrait taken on the XR looks bright, but a bit washed out by the street lights.
The XR cropped in closer, so the street lights didn't get in the way and it has better contrast and colors.