@ravi@robb@gdp Ravi is correct. Music streaming royalties are not a fixed rate per stream.
There is a pool of money that is apportioned to an artist by the number of streams the artist had divided by the total number of streams all artists had.
Apple Music customers seem to not listen nearly as much as Spotify customers. The demographics for each service could also skew why one artist makes more per stream on one service vs another. Most artists earn far more from Spotify than Apple Music.