Disc and disk are both variants of the English word for objects of a generally thin and cylindrical geometry. The differences in spelling correspond both with regional differences and with different senses of the word. For example, in the case of flat, rotational data storage media the convention is that the spelling disk is used for magnetic storage (e.g. hard disks) while disc is used for optical storage (e.g. compact discs, better known as CDs). When there is no clear convention, the spelling disk is more popular in American English, while the spelling disc is more popular in British English.

https://en.wikipedia.org/wiki/Spelling_of_disc

Quoting mreeder50:

Quote:
A hard disk drive that is in you computer is spelled Disk. An optical disc such as DVD, BD, 3DBD, 4K is spelled Disc.

Just some info for anyone who doesn't know the difference.

Please, if I'm wrong and someone has other info, jump in and correct me.

You are absolkutley correct; the use of the "disc" spelling originated with LaserDiscs and Pioneer purposfully using the "incorrect" spelling of disk specifically to different its new product by using a new spelling, similar to a trademark, although while LaserDisc was trademarked, seems everyone picked up that unique spelling to refer to all optical discs.  It was used from then on seems by all hardware and software manufactures for any flat, optical storage device, beginning with the CD.  It persists to this day for all CDs, DVDs, BluRays and 4K discs.  I don't think any major company in the English speaking contries uses "disk" to refer to optical media storace devices.