You can distinguish a trackpad from a mouse, in that stuff like "multi-finger gestures" or "pinch in/out" makes sense on a trackpad but not a mouse. Whereas, a

You can distinguish a trackpad from a mouse, in that stuff like "multi-finger gestures" or "pinch in/out" makes sense on a trackpad but not a mouse. Whereas, a trackball is roughly the same as a mouse. (Albeit, much more comfortable to use, IMO).