Definition
Master vs. Composition
Two separate copyrights live inside every song: the recording (master) and the underlying work (composition). They generate different royalties and pay different people.
The composition is the song — notes, chords, lyrics. Owned by songwriters and their publishers. Generates performance, mechanical, and sync royalties.
The master is one specific recording of that composition. Owned by the performing artist, label, or whoever funded the session. Generates streaming royalties (master side), neighboring rights, and master-use sync fees.
When Spotify pays out a stream, two checks get written — one to the master side, one to the composition side. They flow through entirely different pipes (DSP → distributor → label vs. DSP → MLC/PRO → publisher → songwriter).
SSP stamps the master. Composition rights are handled separately by your PRO and publisher.