There are two levels of canon in Trek, Roddenberry-based, which includes the tv and movie productions, and CBS-endorsed canon, which includes all video games, novels, and the like. Obviously Roddenberry-based is generally viewed as the only legitimate canon by the general fanbase. The canonocity of CBS-endorsed content is still dubious and debatable, so it's probably best to call it all semi-canon.
Also of note is the fact that Star Wars has like half a dozen levels of canon. This ranges from the movies, called G-canon (George Lucas), down to N-canon, which is basically non-canon. The point of having a non-canon level of canonocity is that sometime in the future it may be made canon. For example, the character Aayla Secura was originally comic canon, but everyone liked the idea (and the fact that she was hot) so they made her canon. Not only that, but G-canon, the highest level.