handbook vs reference work

handbook and reference work both are nouns.

Word	Noun	Adjective	Verb	Adverb
handbook	Yes	No	No	No
reference work	Yes	No	No	No

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

handbook: a concise reference book providing specific information about a subject or location
reference work: a book to which you can refer for authoritative facts

Other hypernyms of handbook include book of facts, reference, reference book.

handbook (noun)	reference work (noun)
a concise reference book providing specific information about a subject or location	a book to which you can refer for authoritative facts