St. Eustatius vs island

St. Eustatius and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
St. Eustatius	Yes	No	No	No
island	Yes	No	No	No

St. Eustatius (noun)	island (noun)
an island in the Netherlands Antilles	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water