Emerald Isle vs island

Emerald Isle and island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Emerald Isle	Yes	No	No	No
island	Yes	No	No	No

Emerald Isle (noun)	island (noun)
an island comprising the republic of Ireland and Northern Ireland	a zone or area resembling an island
	a land mass (smaller than a continent) that is surrounded by water