Bioko vs island

Bioko and island both are nouns.

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

Bioko (noun)	island (noun)
an island in the Gulf of Guinea that is part of Equatorial Guinea	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water