Ionic order vs Ionian order

Ionic order and Ionian order both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ionic order	Yes	No	No	No
Ionian order	Yes	No	No	No

As nouns, Ionic order and Ionian order are synonyms defined as:

Ionic order and Ionian order: the second Greek order; the capital is decorated with spiral scrolls

Ionic order (noun)	Ionian order (noun)
the second Greek order; the capital is decorated with spiral scrolls	the second Greek order; the capital is decorated with spiral scrolls