An accomplice refers to a person who in any way helps with the carrying out of a crime. An accomplice to a crime is not the person who commits the crime, but is rather a person that makes committing the crime easier for the person who is actually committing the crime.
In general, a person who is convicted for being an accomplice to a crime will not be punished quite as severely as the person who actually commits the crime. However, this is not always the case. Depending on the crime, an accomplice to a crime can be found just as guilty for a crime as the person who commits the crime. For example, an accomplice to a crime could be punished as much as a person who commits murder if the accomplice helps in hiding the body from authorities.