It's horses for courses. For me, a covers band is a band that does covers. There are variations within that but, like all genres, there are sub genres. Covers bands who are accurate reproductions, bands who expand their covers, tribute bands etc. The definitions are very broad in the way that Louis Armstrong and Ornette Coleman are both Jazz, Status Quo and Trivium are both Rock and Level 42 and Parliament are both funk. The terms are only broad definitions not scientific classifications.