Hmm... I think that's what we call subordinating and coordinating conjunctions? Does that sound right? The coordinating conjunctions are used to join two independent clauses. They are, "and, but, or," and "so". There are also, "for, nor" and "yet," but these are less common. There are a lot of subordinating conjunctions (words that join a dependent clause to an independent clause). I found a quick list from Google on this website: http://englishplus.com/grammar/00000377.htm