Analog trim levers move. You can tell how much trim you have added by either looking at it or by feel. Some guys like to be able to pull their throttle stick all the way back to idle without killing the engine. They will then move the trim to cut the motor off.

Digital trims are like buttons on a calculator. You cannot tell how much you have added. It is hard to use a digital trim button to go below idle because you would have to keep pushing the button (or in some cases, hold it down) but it takes longer and is not convenient. Thus the advent of the cut off switch - where you program a switch to move the throttle that last little bit required to kill the motor.

Not sure which radio manufacturer still makes transmitters with analog trim levers.

Kurt

The photos show analog trim levers. The third photo shows a Tactic transmitter. The throttle trim is analog while the others are digital.