Irish Gaelic vs Goidelic

Irish Gaelic and Goidelic both are nouns.

Word	Noun	Adjective	Verb	Adverb
Irish Gaelic	Yes	No	No	No
Goidelic	Yes	No	No	No

As nouns, Goidelic is a hypernym of Irish Gaelic; that is, Goidelic is a word with a broader meaning than Irish Gaelic:

Irish Gaelic: the Celtic language of Ireland
Goidelic: any of several related languages of the Celts in Ireland and Scotland

Other hypernyms of Irish Gaelic include Erse, Erse language, Gaelic, Gaelic language, Goidelic language.

Irish Gaelic (noun)	Goidelic (noun)
the Celtic language of Ireland	any of several related languages of the Celts in Ireland and Scotland