I am working on an English-language online resource. It seems an obvious good idea to allow users to choose a version in British English or American English spelling. However, I've noticed that spell-checkers also provide options such as Canadian English, Australian English, South-African English, Jamaican English, Hong Kong English, and so on. I have always assumed that these variants are all basically British or American, with maybe a few minor details that are different. So my question is:
Are any of the other variants of English spelling significantly different from British or American spelling?
With significantly different, I mean that they don't just add a number of new words, like "wee" or "bairn" in Scotland, or French loan-words in Canada, but that basic English words are spelled differently, in the way that e.g. "colour/color", "analyse/analyze" and "theatre/theater" are spelled differently in the UK/USA.
(To be clear: I'm only interested in how great the difference is to an outside observer, not how important it is to e.g. a Canadian person to be able to select "Canadian English" instead of having to select "British English". I'm also not interested in differences in grammar.)