> I am not young, and I was around for both. What was the difference?

imo the difference is that spotify at least tried to hide it

when you searched for songs on grooveshark you'd get names back like "Tame Impala - The Slow Rush (2020) Mp3 (320kbps) [Hunter]"

also IIRC grooveshark never even tried to set up revenue share with labels/artists

Spotify cheated behind the scenes and a veneer of following the rules, which eventually transitioned into actually following the rules and paying out artists