I think it's different because it excludes Australia and New Zealand, which are otherwise exactly like North America in that they've inherited their language an

I think it's different because it excludes Australia and New Zealand, which are otherwise exactly like North America in that they've inherited their language and culture from Britain. If you want to talk about the world-wide English-speaking-culturally-British-based-community it's "Anglo-American" that is more wildly incorrect, which makes "Anglo-Saxon" -- denoting the common heritage from a British, English-speaking, culture -- more correct.