In addition to the ability to program the size of your rig into the 760 it also plans your route based on the size of your rig. The 760 knows when you are in RV mode vs. car mode and plans the route accordingly. In addition to clearances it guides you on major routes vs. smaller roads when in RV mode.
The 760 also has a video input that allows you to use the Garmin wireless back up camera. One advantage of the Garmin camera is you do not need another monitor on the dash. The GPS screen serves as both camera screen and GPS screen.
Not trying to sway you towards any model but there are more differences than just clearances.