An accessory gives some kind of aid in the commission of a crime (before or after it - for example, if a mother tries to hide her son's guilt of a murder by hiding the evidence, she's an 'accessory after the fact'). An accomplice is involved either in committing the crime or in planning it.
Felony is an act of crime perpetrated intentionally, for which the law orders the infliction of imprisonment. Any other acts of crime are misdemeanours .
Offence means transgression of the law, usually less serios than felony.
Crime is an instance of negligence that is deemed injurious to the public welfare or morals or to the interests of the state.
Well, I am a little surprise by your definitions. I always thought that felony is that kind of crime that is very hard, like murder ot treason. And crime is something more general. And misdemeanour is a very very light offence like barking dog that disturb peace.
What do you think of that?