Greek vs Ellas

Greek and Ellas both are nouns.

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

Greek (noun)	Ellas (noun)
the Hellenic branch of the Indo-European family of languages	a republic in southeastern Europe on the southern part of the Balkan peninsula; known for grapes and olives and olive oil
a native or inhabitant of Greece

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