manual vs handbook

manual and handbook both are nouns.

Word	Noun	Adjective	Verb	Adverb
manual	Yes	Yes	No	No
handbook	Yes	No	No	No

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

manual: a small handbook
handbook: a concise reference book providing specific information about a subject or location

Other hypernyms of manual include enchiridion, vade mecum.

manual (noun)	handbook (noun)
(military) a prescribed drill in handling a rifle	a concise reference book providing specific information about a subject or location
a small handbook

manual (adjective)	handbook (adjective)
requiring human effort
of or relating to the hands
doing or requiring physical work