The number of megapixels determines the resolution of the images captured with the main camera. A higher megapixel count means that the camera is capable of capturing more details. However, the megapixel count is not the only important element determining the quality of an image.
Cameras with an adjustable FOV allow users to set view angles depending on their needs. A wider FOV captures a larger visible area, but with fewer details. A more narrow field of view captures less but in more detail and is often used for recording content at a distance.
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.
The larger the sensor the more light the sensor captures yielding in better image quality.
With a wider aperture the sensor can capture more light, helping to avoid blur by enabling a faster shutter speed. It also provides a shallow depth of field, allowing you to blur the background to focus attention on the subject.
A multi-lens camera captures two or more images and overlays them. This technology creates sharper images, especially in low light conditions, and allows you to use effects such as softening the background.
A BSI (backside illuminated) sensor is a camera image sensor which captures better quality images in poor lighting conditions, and offers better overall sharpness and image quality.
CMOS image sensors are slowly replacing CCD sensors, due to reduced power consumption and better image quality. They can be very compact and cost relatively little to produce.
The better a device's color depth the more color nuances it can distinguish. Source: DxOMark.