hardback vs hardcover

hardback and hardcover both are nouns.

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

As adjectives, hardback and hardcover are synonyms defined as:

Other synonyms of hardback include hardbacked, hardbound.

As nouns, hardback and hardcover are synonyms defined as:

hardback and hardcover: a book with cardboard or cloth or leather covers

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

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