There are only a few key differences that separate a general contractor (or sub-contractor) from a prime contractor, and these differences are usually dependant on a certain specific project issue.  General (or sub-contractors) are responsible for an entire project, while prime contractors are only responsible for the work delegated in his or her prime contract.  They also assume responsibility, and fault, for any work that he or she assigns to sub-contractors, and has exclusive control over the work quality and payment among other responsibilities concerning said sub-contractors.