Very different. Generally Tyson looked to score brutal power shots to set up head shots. McCallum mixed it up with more consistancy, variety and workrate
McCallum countered from range down there, Tyson didn't go to the body much unless he was setting up the uppercut from the floor.
I'd rather take my chances against McCallum's punches. I'm quite a big man and if i trained hard I might at least live to see another day. Tyson would literally kill.