Twin vs Twin Falls

Twin and Twin Falls both are nouns.

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

As nouns, Twin and Twin Falls are synonyms defined as:

Twin (noun)	Twin Falls (noun)
a waterfall in the Snake River in southern Idaho	a town on the Snake River in south central Idaho near the Twin Falls
(astrology) a person who is born while the sun is in Gemini	a waterfall in the Snake River in southern Idaho