A mechanical trackball tracks the users input by sensing the movements of a ball. This is done using a pair of small wheels at a 90 degree angle from each other which contact the trackball and are moved by the trackball movements. These movements are translated electrical signals by servos and then transmitted to the computer.

An optical trackball tracks the users input by taking optical data from the ball movements. This may consist of an optical sensor similar to the ones used in digital cameras, or may use laser diodes to detect tiny physical features of the trackball movement.

Optical trackball generally have less moving parts than mechanical trackball in addition they have much higher sensitivity.

Generally we recommend mechanical trackball for the application of outdoor and harsh environment, while optical trackball for indoor normal environment.