I don't think Sam actually tried to kill Dean and I don't think Dean thinks so either. Sam had just heard Dean, who was more of a father to him than John ever was, say something that's been Sam's greatest fear since his powers manifested--that Dean thinks he's a monster. In other circumstances, that might have produced some tears. With the demon blood fueling and amplifying Sam's aggression, instead there was a fight that went one step farther than it would have otherwise (it's not like Dean has never punched Sam in anger before). Dean didn't talk Sam out of choking him and he didn't fight his way free. Sam caught himself and let go all on his own before Dean was even unconscious.

It's not so much the events that prompted the words as the reason behind them that are the same. Both John and Dean didn't want Sam going off somewhere where they could no longer protect him. Unfortunately, Sam has a knee-jerk contrarian streak when it comes to ultimatums.