island vs Sumatra

island and Sumatra both are nouns.

Word	Noun	Adjective	Verb	Adverb
island	Yes	No	No	No
Sumatra	Yes	No	No	No

island (noun)	Sumatra (noun)
a zone or area resembling an island	a mountainous island in western Indonesia
a land mass (smaller than a continent) that is surrounded by water