Aren't there people who insist that one kind of thingie is "disc" and another kind is "disk" and this distinction is very important even though the rest of us never even noticed? Like it's a Compact Disc but a floppy disk or something like that?
I found there's a wikipedia page with examples of distinct usages is a bunch of varied fields!
CDs and DVDs and related formats are disCs, floppies and related formats are disKs. and if you wanna be a weirdo about hard drives those can also be hard disKs as well