Gemini vs doer

Gemini and doer both are nouns.

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

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

Other hypernyms of Gemini include actor, worker.

Gemini (noun)	doer (noun)
the third sign of the zodiac; the sun is in this sign from about May 21 to June 20	a person who acts and gets things done
a zodiacal constellation in the Northern Hemisphere between Taurus and Cancer on the ecliptic
(astrology) a person who is born while the sun is in Gemini