declare vs certify

declare and certify both are verbs.

Word	Noun	Adjective	Verb	Adverb
declare	No	No	Yes	No
certify	No	No	Yes	No

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

declare (verb)	certify (verb)
state emphatically and authoritatively	provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
state firmly	declare legally insane
make a declaration (of dutiable goods) to a customs official	guarantee payment on; of checks
declare to be	guarantee as meeting a certain standard
announce publicly or officially	authorize officially
proclaim one's support, sympathy, or opinion for or against
designate (a trump suit or no-trump) with the final bid of a hand
authorize payments of