disk space vs disc space

disk space and disc space both are nouns.

Word	Noun	Adjective	Verb	Adverb
disk space	Yes	No	No	No
disc space	Yes	No	No	No

As nouns, disk space and disc space are synonyms defined as:

disk space and disc space: (computer science) the space available on a magnetic disk

disk space (noun)	disc space (noun)
(computer science) the space available on a magnetic disk	(computer science) the space available on a magnetic disk