"Cover" seems to be a continuum. In it's purest form it's about Pat Boone recording a velveeta cheese version a black artist's song because white radio wouldn't play black music.......and now Pat Boone can make the money the the RnB performer deserved.

Now it seems applied to anybody who records somebody else's material.

It might be an interesting thread (maybe there is one already) just to explore the boundaries of 'cover version'.