telephone directory vs phonebook

telephone directory and phonebook both are nouns.

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

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

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

Other synonyms of telephone directory include phone book, telephone book.

telephone directory (noun)	phonebook (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