Greece vs Ellas

Greece and Ellas both are nouns.

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

As nouns, Greece and Ellas are synonyms defined as:

Greece and Ellas: a republic in southeastern Europe on the southern part of the Balkan peninsula; known for grapes and olives and olive oil

Other synonyms of Greece include Hellenic Republic.

Greece (noun)	Ellas (noun)
a republic in southeastern Europe on the southern part of the Balkan peninsula; known for grapes and olives and olive oil	a republic in southeastern Europe on the southern part of the Balkan peninsula; known for grapes and olives and olive oil
ancient Greece; a country of city-states (especially Athens and Sparta) that reached its peak in the fifth century BCE