Image tracking allows you to recognize an image and place virtual content on it.
Surface tracking identifies horizontal and vertical surfaces and uses them to place virtual content.
Object tracking is a process where the algorithm tracks the movement of an object.
Location tracking is when AR is combined with location based sensors, and GPS to put virtual navigations on real street view.
Face tracking is when the technology can detect that there is a actual face in the frame or can add features to the face which is being scanned.