phone book vs directory

phone book and directory both are nouns.

Word	Noun	Adjective	Verb	Adverb
phone book	Yes	No	No	No
directory	Yes	No	No	No

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

phone book: a directory containing an alphabetical list of telephone subscribers and their telephone numbers
directory: an alphabetical list of names and addresses

phone book (noun)	directory (noun)
a directory containing an alphabetical list of telephone subscribers and their telephone numbers	an alphabetical list of names and addresses
	(computer science) a listing of the files stored in memory (usually on a hard disk)