duplicate vs twin

duplicate and twin both are nouns.

Word	Noun	Adjective	Verb	Adverb
duplicate	Yes	Yes	Yes	No
twin	Yes	Yes	Yes	No

As adjectives, duplicate and twin are synonyms defined as:

Other synonyms of duplicate include matching, twinned.

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

Other hyponyms of duplicate include backup, computer backup, counterpart, similitude, match, mate.

As verbs, duplicate and twin are synonyms defined as:

Other synonyms of duplicate include parallel.

duplicate (noun)	twin (noun)
a copy that corresponds to an original exactly	a duplicate copy
something additional of the same kind	either of two offspring born at the same time from the same pregnancy

duplicate (adjective)	twin (adjective)
being two identical	being two identical
identically copied from an original

duplicate (verb)	twin (verb)
increase twofold	give birth to twins
make or do or perform again	grow as twins
make a duplicate or duplicates of	bring two objects, ideas, or people together
duplicate or match	duplicate or match