The focus motor moves the lens in order to autofocus. For system cameras, having a focus motor in the camera's body allows you to use a wide range of lenses, including lenses which do not have their own focus motor. For compact cameras, a focus motor is usually built-in.
We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
A hot shoe can be used to attach an external flash, as well as light meters, viewfinders, rangefinders and other attachments.
Resolution is an essential indicator of a screen's image quality, representing the maximum amount of pixels that can be shown on the screen. The resolution is given as a compound value, comprised of horizontal and vertical pixels.
A higher screen resolution provides a sharper image, making it easier to review your photos.
A system camera has many interchangeable components such as lenses, flashes, and other accessories. System cameras offer greater flexibility than compact cameras.