assure vs guarantee

assure is not a noun while guarantee is a noun.

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

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

Other hyponyms of assure include pledge, plight, swear off, contract, undertake, undertake.

As verbs, assure and guarantee are synonyms defined as:

Other synonyms of assure include ensure, insure, secure.

assure (noun)	guarantee (noun)
	a written assurance that some product or service will be provided or will meet certain specifications
	an unconditional commitment that something will happen or that something is true
	a collateral agreement to answer for the debt of another in case that person defaults

assure (verb)	guarantee (verb)
be careful or certain to do something; make certain of something	give surety or assume responsibility
inform positively and with certainty and confidence	promise to do or accomplish
assure somebody of the truth of something with the intention of giving the listener confidence	stand behind and guarantee the quality, accuracy, or condition of
make a promise or commitment	make certain of
make certain of