the difference between being the "harder puncher" and being the "better puncher"

In most cases we judge a puncher on how many ko's they have, but thats not the end all be all on judging how good a puncher a fighter is, the best comparison I have is mayweather and cotto. It's proven that cotto is a very hard puncher, however if you look at his Ko's most of them the come as a result of sustained hard punches rarely any one punch ko's, in part because of how he gets off, rarely do you see cotto land punches the opponent does'nt see coming. Mayweather has'nt scored a ko in a long time but based on how he deliveres his punches consistantly "stuns" his opponents more often because they hardly know the punch is coming in advance. The knock downs against hatton and marquez illustrate that point perfectly. If you were to judge strictly on one shot power advantage cotto, but if you judge on placement and how each one of them "gets off" advantage mayweather