A song has two copyrights. It has the copyright that comes from the songwriter and it has the copyright from the performer. They're very different. It creates these two separate rights. They're not always the same person.
Once upon a time, in fact, it was rare that they were the same person. The job of what they called an “A and R” person in the labels, in the sixties and fifties, was to match an artist, A, with repertoire, R. They would bring them together and create great music.
Then came the era of the singer-songwriter, where they merged.
My wife, Margo Timmins, for example, did a very famous cover of a Lou Reed song, Sweet Jane. For years, when that was performed on the air, Lou Reed, the songwriter, got paid, but Margo Timmins, the performer, didn't. That was fixed in 1997, but with a whole slew of exemptions.
Those are the two basic copyrights.