The larger the sensor the more light the sensor captures yielding in better image quality.
35.8 x 23.9mm
Polaroid Snap: 81.2 x 25.4mm
3. focus points
The more focus points the more flexibility in picking which part of the scene to focus on. They also give the image sensor a better probability in identifying the right area of the scene to focus on in more automatic modes.
Sony Alpha a9: 693
The maximum ISO at which the device still captures excellent quality images. Source: DxOMark.
Sony Alpha 7S: 3702ISO
5. has a flip-out screen
Flip-out screens are useful for doing tricky shots.
Sony Alpha 7S
27% have it
HTC Re: 65.5g
7. image quality
A device's overall image quality score considers: color depth, dynamic range and low light performance. Source: DxOMark.
Sony Alpha 7R II: 98
8. maximum light sensitivity
With a higher light sensitivity (ISO level), the sensor absorbs more light. This can be used to capture moving objects using a fast shutter speed, or to take images in low light without using a flash.