Русско-англо-русский юридический словарь

Yes, both 'suit' and 'lawsuit' mean the same thing together, as does 'action.

There is no difference between 'suit' and 'lawsuit' in terms of the law. 'Action' means 'legal action', but not necessarily a suit or lawsuit. 'Action' could mean a range of things in legal terms, like the filing of a lien or other types of legal actions - the point of the 'hold harmless' terminology is to cut off all possible legal avenues, period.

Perhaps combining ''lawsuit and 'suit' into one word, and 'action' another, to denote any and all other legal actions, something finite would be prudent. HTH (ProZ)