The difference between comedy and tragedy is, Aristole says that "Comedies tended to focus on ordinary charaters of a less noble type". This means when Aristole calls the charaters "Ugly" he means that he is clarifing the description of the charater and he wnts it to be funny. Aristole says that "Tragedy is an imitation of and action that is serious and of a certain magnitude". This means that tragedy is something that is dramatic happens and he ses that when something very tragic happens then its labeled as a iminadte action.
