difference between the celts and the gaels?

English Gaul(s), French Gaulois(es), Latin Gallus or Galli, German Gallier might be from an originally Celtic ethnic or tribal name (perhaps borrowed into Latin during the early 400s BC, Celtic expansions into Italy). Its root may be the Common Celtic *galno-power or strength. Greek Galatai (see Galatia in Anatolia) seems to be based on the same root, borrowed directly from the same hypothetical Celtic source which gave us Galli (the suffix -atai is simply an ethnic name indicator). There may also be an element of ancient "fake etymology" in the Greek word "Galatai": "gala" is the Greek word for milk and the Gauls undoubtedly appeared milky-white in complexion compared to darker-skinned Mediterraneans.

The use of the word 'Celtic' as a valid umbrella term for the pre-Roman peoples of Britain has been challenged by a number of writers - including Simon James of the British Museum. His book The Atlantic Celts - Ancient People Or Modern Invention? makes the point that the Romans never used the term 'Celtic' in reference to the peoples of the Atlantic archipelago, i.e the British Isles. He makes it clear that the term was coined as a useful umbrella term in the early 18th century when England united with Scotland to create Great Britain. The Unionists found it expedient to use the hitherto neutral term British for their own imperial ends. Thus a new term was needed to unite nationalists in Scotland, Ireland and Wales. The term 'Celtic' fit the bill. James makes the point that archaeology does not suggest a united Celtic culture and that the term is misleading, no more meaningful than 'Western European' would be today, and is also anachronistic.

However, there are valid linguistic reasons for classifying the languages of Wales, Scotland, and Ireland with those of Brittany and of historical Gaul and Galatia, and 'Celtic' has been adopted by linguists as a term of convenience, since the Celtic nations did not have a standard umbrella term for themselves.