These spellings are the British version:
AUTHORISE - COLOUR
These are the American version:
AUTHORIZE - COLOR
Brits & Canucks may consider that AUTHORISE and COLOUR are the CORRECT spelling. Americans consider that these spellings are neither correct nor incorrect, but simply the BRITISH version, and our spelling is the AMERICAN version.
American democratic ideals can be seen in the position of VERSION as opposed to the position of CORRECTNESS. Loyalty to the British KING can be seen in the BRITISH view of CORRECTNESS as opposed to the American view of VERSION.
This loyalty to the KING can also be seen in how Canadians did not want to be disloyal to England and thus retained their own country loyal to the King, and so retained their preference for British spelling rather than American spelling.
It's also a good thing now that the American spelling version is AUTHORIZE and not AUTHORISE, because with the large number of Hispanics in the USA, one notices certain peculiarities in pronunciation. There is basically no voiced "Z" sound in Spanish when between vowels, so that AUTHORIZE is pronounced AUTHORICE by Hispanics, even those born and raised in the USA. The AUTHORISE spelling would be pronounced AUTHORICED. Thank God for the "Zeeeeeee" which Canadians like to call "Zed."
A noteworthy feature of the American version is also that using the "Z" instead of the "S" for the voiced "S" sound is more phonologically consistent, and eliminating the "U" from words like "colour" is an aspect of linguistic economy. So it cannot be stated with authority that the American versions are "incorrect."