Greek vs Lesbian

Greek and Lesbian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Greek	Yes	Yes	No	No
Lesbian	Yes	No	No	No

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

Greek (noun)	Lesbian (noun)
the Hellenic branch of the Indo-European family of languages	a resident of Lesbos
a native or inhabitant of Greece

Greek (adjective)	Lesbian (adjective)
of or relating to or characteristic of Greece or the Greeks or the Greek language