Caribbean Island vs island

Caribbean Island and island both are nouns.

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

As nouns, island is a hypernym of Caribbean Island; that is, island is a word with a broader meaning than Caribbean Island:

Caribbean Island (noun)	island (noun)
an island in the Caribbean Sea	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water