hard disc vs hard disk

hard disc and hard disk both are nouns.

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

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

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

Other synonyms of hard disc include fixed disk.

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