Ellas vs Greek

Ellas and Greek both are nouns.

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

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

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