affirm vs prove

affirm and prove both are verbs.

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

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

affirm: establish or strengthen as with new evidence or facts
prove: establish the validity of something, as by an example, explanation or experiment

Other hyponyms of affirm include back, back up, vouch, verify, demonstrate, establish, shew, show, document, validate.

affirm (verb)	prove (verb)
establish or strengthen as with new evidence or facts	establish the validity of something, as by an example, explanation or experiment
to declare or affirm solemnly and formally as true	obtain probate of
say yes to	prove formally; demonstrate by a mathematical, formal proof
	provide evidence for
	take a trial impression of
	cause to puff up with a leaven
	increase in volume
	put to the test, as for its quality, or give experimental use to
	be shown or be found to be