pocketbook vs soft-cover book

pocketbook and soft-cover book both are nouns.

Word	Noun	Adjective	Verb	Adverb
pocketbook	Yes	No	No	No
soft-cover book	Yes	No	No	No

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

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

pocketbook (noun)	soft-cover 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