No, those are different (but similar) concepts that refer to different levels/types of participation in a crime. Acting in concert essentially means being at the crime scene while being part of the plan to commit the crime and taking part in at least one element of the crime itself (and is punished as if you committed the whole crime yourself). Aiding/abetting means knowingly advising, encouraging or helping somebody else commit a crime in such a way that you actually contribute to the crime being committed (there are a lot of specific rules and punishments for aiding and abetting different types of crimes such as DWI). Accessory can be either before or after the fact and is fairly similar to aiding/abetting (and is punished differently depending on whether it was before or after the fact).
No answer to these questions is intended to, nor does it, create an attorney-client relationship. There is no substitute for an actual conversation with a licensed attorney about the particular facts and circumstances of your case.