Emerald Isle vs Ireland

Emerald Isle and Ireland both are nouns.

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

As nouns, Emerald Isle and Ireland are synonyms defined as:

Emerald Isle and Ireland: an island comprising the republic of Ireland and Northern Ireland

Other synonyms of Emerald Isle include Hibernia.

Emerald Isle (noun)	Ireland (noun)
an island comprising the republic of Ireland and Northern Ireland	an island comprising the republic of Ireland and Northern Ireland
	a republic consisting of 26 of 32 counties comprising the island of Ireland; achieved independence from the United Kingdom in 1921