Other than size, there are 2 main differences as I see it.
1. 3D - the 73 has it, the 82 doesn't.
2. The 73 has more complete adjustment controls while the 82 has more simplistic controls.
How important each or both of those are is totally up to you. I got the 73742 as I wanted 3D even though I don't use it very much, and I wanted the more complete controls. Now that I've had it a bit, I like the 3D and haven't really needed the more precise controls.