Lots of things really. At first glance the 3/4-ton is longbed and the 1/2-ton is shortbed. For some folks thats enough. The 3/4-ton has a heavier frame, springs, axle ratings and payload capacity. The 1/2-ton has 6-bolt wheels, semi floating 4.10 rear end, a frame that widens as it goes to the rear, and a torque-tube (enclosed) drive shaft among lots of other things. 3/4-ton has 8-bolt wheels, full floating 4.57 rear end, a parallel frame behind the cab and an open drive shaft. Maybe somebody else will think of other things.
I like my 3/4-ton!! That sounds like a good truck. Do you like it? If so you should buy it. Good luck!
