island vs Galveston Island

island and Galveston Island both are nouns.

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

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