duo vs couple

duo and couple both are nouns.

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

As nouns, duo and couple are synonyms defined as:

Other synonyms of duo include duet, twosome.

As nouns, duo and couple are synonyms defined as:

Other synonyms of duo include brace, couplet, distich, duad, duet, dyad, pair, span, twain, twosome, yoke.

duo (noun)	couple (noun)
a musical composition for two performers	a pair who associate with one another
a pair who associate with one another	a pair of people who live together
two performers or singers who perform together	(physics) something joined by two equal and opposite forces that act along parallel lines
two items of the same kind	two items of the same kind
	a small indefinite number

duo (verb)	couple (verb)
	engage in sexual intercourse
	link together
	bring two objects, ideas, or people together
	form a pair or pairs