Viti Levu vs island

Viti Levu and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Viti Levu	Yes	No	No	No
island	Yes	No	No	No

Viti Levu (noun)	island (noun)
a volcanic island in the Fijis, the largest island in Fiji	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water