system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's the difference between sonata, concerto, symphony etc. in classical music?

Who decides which is to be called what?
gpt
Symphony: Full orchestra piece not centred on one instrument.

Concerto: Solo instrument accompanied by an orchestra.

Sonata: Solo instrument usually accompanied by piano (or another keyboard instrument). Can also be a solo keyboard piece.