Answer:
A hero is a person who does something good, while heroism is the actual emotions and reason behing these good or brave actions. An idol is someone who is looked up to by many, even if not all idols are good people. A hero, on the other hand, is generally a good or courageous person. Heroism is the WHY and Heros and Idols and the who.
Explanation:
I did my best, sorry if there aren't three defined differences : /
