island vs New Guinea

island and New Guinea both are nouns.

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

island (noun)	New Guinea (noun)
a zone or area resembling an island	a Pacific island to the north of Australia; the 2nd largest island in the world; the western part is governed by Indonesia and the eastern part is Papua New Guinea
a land mass (smaller than a continent) that is surrounded by water