island vs North Island

island and North Island both are nouns.

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

island (noun)	North Island (noun)
a zone or area resembling an island	the smaller but more populous of two main islands of New Zealand; separated from South Island by Cook Strait
a land mass (smaller than a continent) that is surrounded by water