For copyright purposes, a sound recording differs from a musical composition when a person is applying for copyright status. The US copyright office makes distinction between the two, because a composition is the words and musical notation, while the recording is a form of performance. Additionally, a recording of spoken text, like a book on tape, can also copyrighted even though it's not music.
In order to register for copyright for a musical composition, a performing arts copyright form needs to be filed. Sheet music for the composition needs to be included, and many applicants include a recording of the music being performed. This does not, however, constitute a sound recording.
If a musician is attempting to copyright both the composition of music and a recording at the same time, he or she files a longer sound recording form. That means the specific performance and the material performed are now subject to copyright law. Many musicians work as primarily songwriters, though, and they may only include a recorded song in a performing arts song to further their claim that they have, in fact, written the material.
The distinction often comes down to who gets paid and when. A copyrighted sound recording protects the person holding the copyright from unlawful reproduction of the recording. This might include illegal downloads or file sharing and the unauthorized burning of discs. In general, while the copyright is active, no one can use that particular recording without paying for it — unless the copyright holder actively gives it away.
A performing arts copyright works differently. Anyone wishing to record the song must get permission from the composer. As long as the copyright holds, the composition cannot be used without payment or without permission. Unless the composer sells the copyright, he or see maintains full rights to its sole use. He may license the composition for use in a sound recording, and in general, he will be paid for such licensing.
There are several notable musicians who have written music without performing it,including the Bee Gees, Lionel Ritchie, and Burt Bacharach. Even though they did not perform some of their compositions, they always had the right to do so if they wished. They licensed use of their compositions for others who made recordings.
For example, the Dolly Parton/Kenny Rogers duet “Islands in the Stream” is a composition by Barry, Robin, and Maurice Gibb. The producers of the song paid the Gibbs to use the composition on a record. Filing a sound recording form then copyrighted that performance. The Gibbs could perform the song in concert, however, or even record their own version. All the artists involved were paid accordingly: Dolly Parton and Kenny Rogers were paid a portion of the sales of the record for their performance, and the Gibbs were paid for licensing the song.
If anyone had illegally copied the recording of Parton and Rogers, it would have been up to the producers of the song to seek legal redress. Alternately, if someone performed “Islands in the Stream” without permission from the Gibbs, this would have been a violation of the performing arts copyright. The Bee Gees would have been responsible for seeking any damages incurred by this violation.