Sicily vs island

Sicily and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sicily	Yes	No	No	No
island	Yes	No	No	No

Sicily (noun)	island (noun)
the Italian region on the island of Sicily	a zone or area resembling an island
the largest island in the Mediterranean	a land mass (smaller than a continent) that is surrounded by water