Sicilian vs Italian

Sicilian and Italian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sicilian	Yes	Yes	No	No
Italian	Yes	Yes	No	No

As nouns, Italian is a hypernym of Sicilian; that is, Italian is a word with a broader meaning than Sicilian:

Sicilian (noun)	Italian (noun)
a resident of Sicily	the Romance language spoken in Italy
	a native or inhabitant of Italy

Sicilian (adjective)	Italian (adjective)
of or relating to or characteristic of Sicily or the people of Sicily	of or pertaining to or characteristic of Italy or its people or culture or language