That is what I though also. One big difference is that WK put his body behind his punches and executes them textbook style. What VK does is arm punching which is faster and easier to throw without any leg or body movement (and you can throw many of them). I would say both have very good footwork, I would give the edge to WK because of his impeccable sense of distance. Nevertheless, I prefer watching VK who is bound to get tagged a couple of time with his style, especially now when he has slowed down a bit. Don't remember when was WK tgged with a punch... he's so good that it is boring.
I think is ability to, as you said, be so aggressive, and also be so effective at slipping outta range and causing his opponent missed shots is not often seen in a heavyweight. And to be so effective at 39 is a testament to his dedication to training and conditioning.
It is not. It takes much more skill to do the things Tyson did than the pulling back of Vitali. Boxing has always been easier for the taller man who has the reach advantage bacause it is mcuh easier to see punches and defend against them. Only thing Vitali does, is pull back and counter with a right hand or a left hook. That may work against slow, plodding smaller guys like Peter, Arreola and Willams.