Saint Lucia vs island

Saint Lucia and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Lucia	Yes	No	No	No
island	Yes	No	No	No

Saint Lucia (noun)	island (noun)
a country on the island of Saint Lucia; gained independence from Great Britain in 1979	a zone or area resembling an island
a volcanic island in the Windward Isles to the south of Martinique	a land mass (smaller than a continent) that is surrounded by water