sweeten vs candy

sweeten is not a noun while candy is a noun.

Word	Noun	Adjective	Verb	Adverb
sweeten	No	No	Yes	No
candy	Yes	No	Yes	No

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

Other hyponyms of sweeten include honey, saccharify, sugar, glaze, sugarcoat, mull.

sweeten (noun)	candy (noun)
	a rich sweet made of flavored sugar and often combined with fruit or nuts

sweeten (verb)	candy (verb)
make sweeter, more pleasant, or more agreeable	coat with something sweet, such as a hard sugar glaze
make sweeter in taste