Hokkaido vs island

Hokkaido and island both are nouns.

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

Hokkaido (noun)	island (noun)
the second largest of the four main islands of Japan; to the north of Honshu	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water