Twin vs doer

Twin and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Twin	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of Twin; that is, doer is a word with a broader meaning than Twin:

Other hypernyms of Twin include actor, worker.

Twin (noun)	doer (noun)
a waterfall in the Snake River in southern Idaho	a person who acts and gets things done
(astrology) a person who is born while the sun is in Gemini