The main difference is that if you as a person learn music, or play video games, or anything else where you take someone else's work and make it your own, you are making it your own.

ChatGPT and other AI like it only regurgitate their training data in a mishmash of almost, but not quite, nonsense. There's no "reimagining" there's no creativity, it's just a literal rehash of the training data.

It's even in the name, the P in ChatGPT stands for "pre-trained". It isn't learning anything new, it's just spitting out bits and pieces of what you originally fed it, and that is copyright infringement with extra steps.