[chalupa-man]

I've always thought of aggression as something qualitatively different. To me assertive behaviour is behavior in pursuit of some objective, whether or not it's sensible or effective, while aggressive behaviour is about the experience of aggression itself, not needing a goal. Things like road rage, school bullying, wrecking stadiums and yelling at players after football matches, where the behaviour isn't intended to achieve anything except the direct effects of being aggressive (expression of anger, feeling big, making others suffer or feel afraid). I would say that someone can be incompetently and rudely assertive, or quietly and competently aggressive.