Look at a typlical Apple Music profile. It classifies every album as "Albums", "Singles & EPs", and "Compilations".
Now look at a typical Spotify profile. It too classifies every album as "Albums", "Singles & EPs", and "Compilations".
But look at "Avril Lavigne".
According to the Apple Music page, her 2013 self-titled album is under "Complilations".
But this is incorrect, her 2013 self-titled album is not a compilation album. It is her sixth LP. The spotify page correctly lists this album under "Albums".
In any case, nether Apple Music nor Spotify are reliable for this classification.
I didn't really understand why the Apple Music page and the Spotify page sometimes contradict each other this way.