Irish capital vs capital of Ireland

Irish capital and capital of Ireland both are nouns.

Word	Noun	Adjective	Verb	Adverb
Irish capital	Yes	No	No	No
capital of Ireland	Yes	No	No	No

As nouns, Irish capital and capital of Ireland are synonyms defined as:

Irish capital and capital of Ireland: capital and largest city and major port of the Irish Republic

Other synonyms of Irish capital include Dublin.

Irish capital (noun)	capital of Ireland (noun)
capital and largest city and major port of the Irish Republic	capital and largest city and major port of the Irish Republic