fixed disk vs hard disc

fixed disk and hard disc both are nouns.

Word	Noun	Adjective	Verb	Adverb
fixed disk	Yes	No	No	No
hard disc	Yes	No	No	No

As nouns, fixed disk and hard disc are synonyms defined as:

fixed disk and hard disc: a rigid magnetic disk mounted permanently in a drive unit

Other synonyms of fixed disk include hard disk.

fixed disk (noun)	hard disc (noun)
a rigid magnetic disk mounted permanently in a drive unit	a rigid magnetic disk mounted permanently in a drive unit