The larger the sensor the more light the sensor captures yielding in better image quality.
6.17 x 4.55mm
Polaroid Snap: 81.2 x 25.4mm
13.2 x 8.8mm
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
4. continuous shooting at high resolution
Fast continuous shooting is useful for catching action shots.
Olympus OM-D E-M1 Mark II: 60fps
The maximum ISO at which the device still captures excellent quality images. Source: DxOMark.
Sony Alpha 7S: 3702ISO
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.