Galveston Island vs island

Galveston Island and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Galveston Island	Yes	No	No	No
island	Yes	No	No	No

Galveston Island (noun)	island (noun)
an island at the entrance of Galveston Bay	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water