deuce vs duo

deuce and duo both are nouns.

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

As nouns, duo is a hyponym of deuce; that is, duo 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
duo: two items of the same kind

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

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