source book vs book of facts

source book and book of facts both are nouns.

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

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

source book: a collection of historically important documents published together as a book
book of facts: a book to which you can refer for authoritative facts

Other hypernyms of source book include reference, reference book, reference work.

source book (noun)	book of facts (noun)
a collection of historically important documents published together as a book	a book to which you can refer for authoritative facts