pocketbook vs paper-back book

pocketbook and paper-back book both are nouns.

Word	Noun	Adjective	Verb	Adverb
pocketbook	Yes	No	No	No
paper-back book	Yes	No	No	No

As nouns, paper-back book is a hypernym of pocketbook; that is, paper-back book is a word with a broader meaning than pocketbook:

Other hypernyms of pocketbook include paperback, paperback book, soft-cover, soft-cover book, softback, softback book.

pocketbook (noun)	paper-back book (noun)
a container used for carrying money and small personal items or accessories (especially by women)	a book with paper covers
pocket-sized paperback book
a pocket-size case for holding papers and paper money
your personal financial means