handbook vs reckoner

handbook and reckoner both are nouns.

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

As nouns, reckoner is a hyponym of handbook; that is, reckoner is a word with a more specific, narrower meaning than handbook:

handbook: a concise reference book providing specific information about a subject or location
reckoner: a handbook of tables used to facilitate computation

Other hyponyms of handbook include manual, bible, guide, guidebook, ready reckoner.

handbook (noun)	reckoner (noun)
a concise reference book providing specific information about a subject or location	a handbook of tables used to facilitate computation
	an expert at calculation (or at operating calculating machines)