couplet vs deuce

couplet and deuce both are nouns.

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

As nouns, deuce is a hypernym of couplet; that is, deuce is a word with a broader meaning than couplet:

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

Other hypernyms of couplet include 2, II, two.

couplet (noun)	deuce (noun)
a stanza consisting of two successive lines of verse; usually rhymed	one of the four playing cards in a deck that have two spots
two items of the same kind	a word used in exclamations of confusion
	the cardinal number that is the sum of one and one or a numeral representing this number
	a tie in tennis or table tennis that requires winning two successive points to win the game