Grecian vs European

Grecian and European both are nouns.

Word	Noun	Adjective	Verb	Adverb
Grecian	Yes	Yes	No	No
European	Yes	Yes	No	No

As nouns, European is a hypernym of Grecian; that is, European is a word with a broader meaning than Grecian:

Grecian (noun)	European (noun)
a native or resident of Greece	a native or inhabitant of Europe

Grecian (adjective)	European (adjective)
of or relating to or characteristic of Greece or the Greeks or the Greek language	of or relating to or characteristic of Europe or the people of Europe