A boxing punch is probably more powerful than a karate punch, all other things being equal. Can you really see a Karateka hitting with more force than a heavyweight boxer? However, whilst boxing might have more power they are slower because they are hooks, at least the most powerful punches are, and boxing relies partly on throwing as many as possible and working on probability. Being a stright line, a karate punch HAS to be faster than a hook, and generally, karate pucnhes are "cleaner" when they hit than in boxing. In terms of raw power, I would definatly say boxers can hit harder (all other things being equal, eg. the same strength, skill etc)