wordbook vs reference book

wordbook and reference book both are nouns.

Word	Noun	Adjective	Verb	Adverb
wordbook	Yes	No	No	No
reference book	Yes	No	No	No

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

Other hypernyms of wordbook include book of facts, reference, reference work.

wordbook (noun)	reference book (noun)
a reference book containing words (usually with their meanings)	a book to which you can refer for authoritative facts