Twins vs Gemini

Twins and Gemini both are nouns.

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

As nouns, Twins and Gemini are synonyms defined as:

Twins and Gemini: the third sign of the zodiac; the sun is in this sign from about May 21 to June 20

Other synonyms of Twins include Gemini the Twins.

Twins (noun)	Gemini (noun)
the third sign of the zodiac; the sun is in this sign from about May 21 to June 20	the third sign of the zodiac; the sun is in this sign from about May 21 to June 20
	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