Mostly it's a matter of spelling, Ranie. After the American Revolution, Americans decided to change a lot of spellings in a childish attempt to prove they were different than the British. The biggest differences are that a lot of words with an 'ou' like colour or labour are spelled with just an 'o' in America, and a lot with 'ae' are supposed to just be 'e'. That said, I only learned last week that the appropriate American spelling of archaeology is archeology when it came up with squiggly red lines under it. I promptly laughed in my computer's face, because I don't think any archaeologist spells it with only one a.