We have simple, compex and coordinated sentences.
When two simple sentences are joined by and/or/but, it becomes a coordinated sentence
When two simple sentences are joined by another conjunction (because, when, if, unless, etc) or a relative pronoun (who, whose, that), it becomes a complex sentence
Complex sentences have a main and a dependent clause. The dependent clause starts after the conjunction.
Coordinated sentences also have two clauses (clause 1 and 2)