directory vs book of facts

directory and book of facts both are nouns.

Word	Noun	Adjective	Verb	Adverb
directory	Yes	No	No	No
book of facts	Yes	No	No	No

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

Other hypernyms of directory include reference, reference book, reference work.

directory (noun)	book of facts (noun)
an alphabetical list of names and addresses	a book to which you can refer for authoritative facts
(computer science) a listing of the files stored in memory (usually on a hard disk)