Basically, the transmitters are identical. Some differences include locations of a few switches on the top of the transmitter, the ratchet on the throttle, and the programming default when the transmitter is first turned on. Futaba makes the two different transmitters because there are people who just have to have a "heli" transmitter if they are primarily a heli flyer. However, it's super easy to move the switches around on the 14MZ

Changing the ratchet on the throttle is descibed on page 17 of the instruction manual.