New Caledonia vs island

New Caledonia and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
New Caledonia	Yes	No	No	No
island	Yes	No	No	No

New Caledonia (noun)	island (noun)
an island to the to the east of Australia and to the north of New Zealand	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water