fake book vs postiche

fake book and postiche both are nouns.

Word	Noun	Adjective	Verb	Adverb
fake book	Yes	No	No	No
postiche	Yes	No	No	No

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

fake book: a fake in the form of an imitation book; used to fill bookcases of people who wish to appear scholarly
postiche: something that is a counterfeit; not what it seems to be

Other hypernyms of fake book include fake, sham.

fake book (noun)	postiche (noun)
a fake in the form of an imitation book; used to fill bookcases of people who wish to appear scholarly	something that is a counterfeit; not what it seems to be
	a covering or bunch of human or artificial hair used for disguise or adornment