It's more than a track but less than an album. If I just want to play Vivaldi's "Summer" that's typically done as 3 tracks for the 1 song. But the album it is on will almost always be the full 4 seasons suite, consisting of 4 songs / 12 movements (tracks). I can also see all the hundreds of different recordings of just those 3 movements in Summer.

There may be several layers of grouping, particularly for opera. There are multiple acts per opera, multiple scenes per act, and there may be multiple songs per scene. If you try and list these as a single "album" you end up with abominations like my favorite recording of Die Walküre with 53 tracks. They try and stick everything in the track name, but on mobile this sometimes hides important information behind the "...".