Eire vs. Erin — What's the Difference?

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Erin is a Hiberno-English word for Ireland originating from the Irish word "Éirinn". "Éirinn" is the dative case of the Irish word for Ireland, "Éire", genitive "Éireann", the dative being used in prepositional phrases such as "go hÉirinn" "to Ireland", "in Éirinn" "in Ireland", "ó Éirinn" "from Ireland".

The Irish name for Ireland; the name used in 1937 to 1949 for the Republic of Ireland.

An early, and now a poetic, name of Ireland.

A republic consisting of 26 of 32 counties comprising the island of Ireland; achieved independence from the United Kingdom in 1921