Both street kids, both had troubled lives but the true differences lie in how they were instructed on how to deal with their anger.
Bruce was instructed with a more philosophical sense of things bringing his body and mind together, making a more complete fighter, where as Mike was instructed on how to deal the most damage in the least amount of time.
The reason I called Mike a one trick pony, it was that he relied heavily on his power punches there were no jabs to speak of and little if no foot work involved, he stood there and pounded you. The reason he started losing was simple, guys started "boxing" him instead of slugging it out {which most could see, wasn't the best choice of actions} and what happened...he lost not only the fight but his temper and respect. Even Freddy Roach, who is arguably the best trainer in boxing had trouble teaching Mike the finer points of boxing.
I'm not saying that this fight would be an easy one for either of them, but given the training and discipline involved by both parties and the resulting skill set, Bruce wins for having a more varied approach.