reference book vs book of facts

reference book and book of facts both are nouns.

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

As nouns, reference book and book of facts are synonyms defined as:

reference book and book of facts: a book to which you can refer for authoritative facts

Other synonyms of reference book include reference, reference work.

reference book (noun)	book of facts (noun)
a book to which you can refer for authoritative facts	a book to which you can refer for authoritative facts