paperback book vs volume

paperback book and volume both are nouns.

Word	Noun	Adjective	Verb	Adverb
paperback book	Yes	No	No	No
volume	Yes	No	No	No

As nouns, volume is a hypernym of paperback book; that is, volume is a word with a broader meaning than paperback book:

Other hypernyms of paperback book include book.

paperback book (noun)	volume (noun)
a book with paper covers	physical objects consisting of a number of pages bound together
	the magnitude of sound (usually in a specified direction)
	the property of something that is great in magnitude
	a publication that is one of a set of several similar publications
	the amount of 3-dimensional space occupied by an object
	a relative amount