Functionally, I can't tell much difference, if any. The VX-3 is a couple ounces lighter than the VX-R, but the VX-R has the Fire Dot reticle, if that is really any advantage.
The MSRP on the VX-R is $624.00, and on the VX-3, $499.00. I have grown quite fond of the 1.75-6x32, and I'll use that scope on most hunting rifles that I have to scope or re-scope in the future. Only specialized rifles will get something else.