The principal is the person who directly plans or commits a criminal offense, whereas an accessory aids the principal once the crime is done. Three other key differences are: 1) The principal typically has criminal intent to commit an offense, while an accessory may not have been aware that the offense even occurred until after it was done. 2) The principal is physically present at the scene of the crime, while the accessory may or may not be in the vicinity at all. 3) The principal bears criminal liability for the offense, while an accessory only faces charges for their role in helping the principal after the offense is committed.