It was a surprise to me too that there are different versions of Irish Gaelic. Very complicated!

Basically, there are two Gaelic language branches - the Brythonic, or "p" Celtic, and the Goidelic, or "q" Celtic branches. These names derive from the ending consonant for "son of" - Mac, or Mc in the "q" Celtic, Ap in the "p" Celtic. Welsh, Breton and Cornish are Brythonic. Irish Gaelic, Scots Gaelic and Manx are Goidelic. I'm not a fluent speaker in any of these languages, but it seems to me like the q Celtic languages are very similar - Irish and Scots Gaelic the most similar of them all.

It's very interesting to see how people are trying to keep these languages alive - the Welsh have probably the most solid language presence, with Breton being a close second. Irish is struggling. Scots is almost extinct, although there's a fierce revivalist movement. The last native speaker of Manx died in the '70's, although there are some few speakers today. Cornish has been extinct, I believe, since the 1600's, although there are a few "scholastic" speakers.

Morgannon