Honshu vs island

Honshu and island both are nouns.

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

Honshu (noun)	island (noun)
the central and largest of the four main islands of Japan; between the Sea of Japan and the Pacific Ocean; regarded as the Japanese mainland	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water