I think it's similar. Some guys are just harder strikers than others.
Mechanically it can look like they're doing the same thing. But the end result isn't the same. Could be down to a bunch of factors. The area and range of the strike, the target that's being hit, how committed the person throwing the strike is.
A guy can have a ferocious right hand against opponents his height or shorter, but he seems feather fisted fighting someone who is a few inches taller because the taller guys chin isn't inside the power arc of the guys swing.
Crocop and Andy Hug were pretty good kickers. Anderson Silva can whack pretty good with his knees. If I remember right, he won his title off a Muai Thai clench knee combo. Guy he knocked out got a rematch and then ktfo with the same move again.