It's a bit like saying "what's the difference betwen an English accent and a Celtic accent" in speech.
You can't answer that: you have to find a different question to ask.

Seven languages mentioned in this thread*, regional dialects everywhere, and at least as much variation in the way traditional music is played and sung.

Anahata
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* English, Irish and Scottish Gaelic, Welsh, Cornish, Manx, Cumbric. Not to mention the non-Gaelic "Scots" which is officially recognised as a language too...