Arran = large, well-populated island accessed by crappy ferry service fronm Ardrossan, Ayrshire.

Aran Isles - three small islands off the coast of Co Galway/Clare & the source of the famous ARAN sweaters.

just for more confusion, there is another small Aran Island off the Donegal coast- not sure if there's any knitting tradition, but not as worn by the Clancy Brothers.