phonebook vs telephone directory

phonebook and telephone directory both are nouns.

Word	Noun	Adjective	Verb	Adverb
phonebook	Yes	No	No	No
telephone directory	Yes	No	No	No

As nouns, phonebook and telephone directory are synonyms defined as:

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

Other synonyms of phonebook include phone book, telephone book.

phonebook (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