affirm vs attest

affirm and attest both are verbs.

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

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

affirm: to declare or affirm solemnly and formally as true
attest: authenticate, affirm to be true, genuine, or correct, as in an official capacity

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

affirm (verb)	attest (verb)
establish or strengthen as with new evidence or facts	authenticate, affirm to be true, genuine, or correct, as in an official capacity
to declare or affirm solemnly and formally as true	provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
say yes to	give testimony in a court of law
	establish or verify the usage of