Emerald Isle vs Hibernia

Emerald Isle and Hibernia both are nouns.

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

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

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

Other synonyms of Emerald Isle include Ireland.

Emerald Isle (noun)	Hibernia (noun)
an island comprising the republic of Ireland and Northern Ireland	an island comprising the republic of Ireland and Northern Ireland