Almost all pop music is released on an album or single basis (I’ll throw in a lot of pop themed music without judgment). All in all, the song stands on its own. You might have a few different shows of the same band/musician (live, unplugged etc.) and maybe a few songs.

Classical music is almost always released on an album basis. An album alone is not nearly a logical division of a classic work. A classical work usually consists of a number of connected pieces that often have an individual name or tempo cue. This is the first thing that goes wrong when you want to search for a specific piece.

In addition, there are different versions. Sometimes also from the same orchestra, say the Concertgebouw Orchestra, from the same piece only with different conductors. For example, Mahler’s Fifth Symphony has been put on CD several times:

• With Mariss Jansons as lead (RCO Live)
• With Riccardo Chile as captain (Deca)
• With Bernard Haitink as captain (Phillips)

It gets even more fun with Bruckner’s symphonies. Bruckner was quite insecure and made different versions of several symphonies. For example, there are at least 3 different versions of the Third Symphony in circulation.

In addition, there are also transcribed (performed on another instrument) pieces. For example for a smaller orchestra or a piano.

These are all things that don’t play a role more or less with other types of music. And now it’s often solved by putting all the information in the song titles. This makes it mysterious.