attest vs affirm

attest and affirm both are verbs.

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

As verbs, affirm is a hypernym of attest; that is, affirm is a word with a broader meaning than attest:

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

Other hypernyms of attest include assert, aver, avow, swan, swear, verify.

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