The larger the sensor the more light the sensor captures yielding in better image quality.
23.6 x 15.6mm
Polaroid Snap: 81.2 x 38mm
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 a6500: 425
The maximum ISO at which the device still captures excellent quality images. Source: DxOMark.
Sony Alpha 7S: 3702ISO
5. continuous shooting at high resolution
Fast continuous shooting is useful for catching action shots.
Olympus OM-D E-M1 Mark II: 60fps
6. has a flip-out screen
Flip-out screens are useful for doing tricky shots.
Optical image stabilization uses gyroscopic sensors to detect the vibrations of the camera. The lens adjusts the optical path accordingly, ensuring that any type of motion blur is corrected before the sensor captures the image.
An optical viewfinder (or OVF) allows the photographer to compose a shot while seeing exactly what the lens sees. There is no time lag and they require no power - as opposed to electronic viewfinders which can drain battery life. They are also better in low light situations.