deuce vs duet

deuce and duet both are nouns.

Word	Noun	Adjective	Verb	Adverb
deuce	Yes	No	No	No
duet	Yes	No	No	No

As nouns, duet is a hyponym of deuce; that is, duet is a word with a more specific, narrower meaning than deuce:

deuce: the cardinal number that is the sum of one and one or a numeral representing this number
duet: two items of the same kind

Other hyponyms of deuce include craps, snake eyes, brace, couple, couplet, distich, duad, duo, dyad, pair, span, twain, twosome, yoke.

deuce (noun)	duet (noun)
one of the four playing cards in a deck that have two spots	(ballet) a dance for two people (usually a ballerina and a danseur noble)
a word used in exclamations of confusion	a musical composition for two performers
the cardinal number that is the sum of one and one or a numeral representing this number	a pair who associate with one another
a tie in tennis or table tennis that requires winning two successive points to win the game	two performers or singers who perform together
	two items of the same kind