affirm vs assure

affirm and assure both are verbs.

Word	Noun	Adjective	Verb	Adverb
affirm	No	No	Yes	No
assure	No	No	Yes	No

As verbs, assure is a hyponym of affirm; that is, assure is a word with a more specific, narrower meaning than affirm:

Other hyponyms of affirm include hold, claim, take, attest, declare, protest, tell.

affirm (verb)	assure (verb)
establish or strengthen as with new evidence or facts	be careful or certain to do something; make certain of something
to declare or affirm solemnly and formally as true	inform positively and with certainty and confidence
say yes to	assure somebody of the truth of something with the intention of giving the listener confidence
	make a promise or commitment
	make certain of