New Ireland vs island

New Ireland and island both are nouns.

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

New Ireland (noun)	island (noun)
an island in the Bismarck Archipelago; part of Papua New Guinea	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water