Exactly how charges are defined varies with the state where the charge is brought. In some states, there is no distinction between criminal and traffic misdemeanors, and in others there is.
Misdemeanor definitions vary from state to state. Some states use letters to denote the different classes and some use numbers. For a good example and explanation see the related link below.
Well, its not a good thing. The only thing you need to know about stuff like that is not to do it... Unless you are a lawyer or something but then you should have just paid more attention at lawyer...