Just look at this photo taken from both a Nexus phone and a Galaxy Note 7. (Sorry it's a bit, er, crooked. I was a beer or two deep.) The Nexus 6P has a 12.3 MP rear camera with 1.55 μm (if you don't understand what that means, just know that has big ass sensors that can capture more in low light than most).
The Note 7, on the other hand, has just a 12 MP rear camera, but with f/1.7 aperture (compared to the Nexus' inferior f/2.0 aperture). The Note photo is bright and vivid, while the Nexus's is a bit underexposed. It has impressive optical image stabilization and finds focus very quickly.
The camera is also where the most obvious UI improvements were made. Samsung continues to simplify and modernize its software design, and it makes using the phone a much more pleasant experience. In the camera app, for instance, there are time-saving new gestures. You can simply swipe up or down to switch between the rear and selfie cameras. You can also swipe left or right to access more advanced camera settings or different filters.