Assertiveness is useful in many areas in life, such as achieving a goal or not letting others walk all over you. However, many people mistake assertiveness for aggression. Aggressive people often bluster or make a lot of noise over any and everything, often complaining to the wrong person. For example, scolding the secretary at the phone company, when it was a tree that took out the phone lines. On the other hand, some people behave aggressively because they may have failed to stand up for themselves in the past, and now will do so any time they feel threatened — whether the threat is real, or even if it’s not the best reaction.
Read the full article here: Assertiveness Vs. Aggressiveness Psychology Today