Saint Kitts vs island

Saint Kitts and island both are nouns.

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

Saint Kitts (noun)	island (noun)
the largest of the islands comprising Saint Christopher-Nevis	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water