There’s been some movement over time but in general disk was used for pc because you had Hard Disk Drives. Then their counterpart the floppy diskette (disks).

Disc as a term was used for media like compact discs and subsequently digital video discs, etc. and then pc components allowing them to be read and then written to did exist for PC’s and, as such, had the disc moniker. But that’s because they were already “discs” branding wise.

USB thumb drives, being created as portable removable media for pc’s were a kind of solid state disk and so they use the k. Even NVME, being primarily storage for computing devices, can also colloquially be called “disks” but more and more people just refer to them as drives and I suspect those who refer to them as disks may do so out of older computer hardware habits and that utilities (fdisk, df, etc)call any such media a “disk”.

Disc seems to be anything with a round and flat outer appearance, where disk seems to refer to any other storage media

I think they're the same word, though.

You know "disc" is actually a weird word.

Like say it a few times out loud

D I S C

Everything on the left is a drive, but only half of them are disks:

Hard Disk Drive

USB pen drive

Floppy Disk Drive

Solid State Drive

My system's locale is set to Esperanto so when I insert a CD, it says Sona KD (Kompakta disko).

Disk is short for diskette

Same word. Different dialects.