hardbacked vs hardcover

hardbacked is not a noun while hardcover is a noun.

Word	Noun	Adjective	Verb	Adverb
hardbacked	No	Yes	No	No
hardcover	Yes	Yes	No	No

As adjectives, hardbacked and hardcover are synonyms defined as:

Other synonyms of hardbacked include hardback, hardbound.

hardbacked (noun)	hardcover (noun)
	a book with cardboard or cloth or leather covers

hardbacked (adjective)	hardcover (adjective)
having a hard back or cover	having a hard back or cover