Well, some words such as blond and blonde have French roots. French is a gender dominant language so blond is used for guys and blonde for females. This way you can distinguish the subject of a sentence's gender. Words like color and colour are simply regional differences.
It England we keep the u. America seems not to like it. Also we use centre, I believe it's center for you.
We also keep our ae whereas I think America drops the a. Pimd related word....here it's paedophile rather than pedophile.
Technically people who live in the states speak American English and Australians speak Australian English