The Hoth AT-ST is actually a 100% different model. It stands taller on its legs when walking compared to the Endor AT-ST, and the head is thinner/smaller overall.
The Vintage AT-ST is actually based on the ESB model design (obviously because it came out in 1980 prior to ROTJ opening). On it there's the little helmet/horns logo on the side and things, just like the toy.
The Endor AT-ST then sits more squat, it lacks the little tabs holding the ankle tight on the back, and other things... The new AT-ST mold is based on the Endor one. The original AT-ST was actually NOT intended to be used till Lucas saw it and liked it a lot. He then insisted they keep the design and add it into the FX shots.
EU's got a lot more designs too... Some full cockpit changes, some just different weaponry to the existing "frame". Marvel was notorious for this. They did a lot of different designs for different vehicles, actually, but the AT-ST seems to have the most variety in EU for some reason. *shrugs*
I wouldn't count on the Hoth AT-ST being done accurately though, to that model. I'd dig it, but I just don't think it'll ever happen. The differences are really significant, especially if you ever see both models side-by-side. A possible reason for the differences is that the ESB Model/Design was destroyed. This happened a lot more than people realize... The Y-Wings seen on tours, or in many archive photos, are not originals... All ANH YW's were destroyed or thrown away. YW's in ESB and ROTJ then are technically new builds.