Gold = a master that is ready to duplicate, if a game has "gone gold" is has / is about to be sent off to the CD pressing plant.
Final or Release Candidate = not quite gold yet, features are supposed to be frozen and there are supposed to be no known outstanding bugs (that are going to be fixed anyway). It's much closer to complete than just a beta, and ready for one last round of testing before declaring it gold.
For a really complex product like a Microsoft server, it might go through several release candidates before going gold, as people keep finding less obvious bugs that still need to be fixed before going to wide distribution.