My son & stepson cant get along!! Any advice?

My 9 year old son and my 10 yr old stepson cannot get along. They have 2 totally different personality types and they clash on every level! One is extremely competitive, physical, and athletic while the other is none of the above! The problem is that my husband feels that even though my son doesn't like to play rough or "get roughed up" (as he would call it) he says he should just man up and take it because, thats what boys need, and its preparing him for real life! Anyone have advice on how we can merge the 2 into some sort of compromise or something? Its total chaos everyday, and i feel like my son shouldnt have to deal with his stepbrother putting his hands on him when he has no right to do so, the conflict is causing major drama in our house!!!