British English is Colour, Centre, Licence etc
American English is Color, Center, License etc

I was always told in the USA's crazy bid to be as little British as possible despite being British changed words and spellings, like Zee, it's the letter ZED. All other countries speak British English though, we invented the language so you speak it, not try inventing your own. But it's wierd that Canada and Australia got it and we didn't.