island vs Vancouver Island

island and Vancouver Island both are nouns.

Word	Noun	Adjective	Verb	Adverb
island	Yes	No	No	No
Vancouver Island	Yes	No	No	No

island (noun)	Vancouver Island (noun)
a zone or area resembling an island	an island off southwestern Canada (off the southwestern coast of British Columbia); the largest island off the west coast of North America
a land mass (smaller than a continent) that is surrounded by water