phone book vs telephone directory

phone book and telephone directory both are nouns.

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

As nouns, phone book and telephone directory are synonyms defined as:

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

Other synonyms of phone book include phonebook, telephone book.

phone book (noun)	telephone directory (noun)
a directory containing an alphabetical list of telephone subscribers and their telephone numbers	a directory containing an alphabetical list of telephone subscribers and their telephone numbers