Ionian vs Attica

Ionian and Attica both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ionian	Yes	Yes	No	No
Attica	Yes	No	No	No

Ionian (noun)	Attica (noun)
the ancient Greek inhabitants of Attica and related regions in Ionia	the territory of Athens in ancient Greece where the Ionic dialect was spoken
a member of one of four linguistic divisions of the prehistoric Greeks, spoken in the central west coast of Asia Minor, the islands of Chios and Samos, islands across the central Aegean, and on the large island of Euboea north of Athens

Ionian (adjective)	Attica (adjective)
of or pertaining to the ancient Ionians who lived in Attica and related territories, to their Ionic dialect of Greek, or to their culture