Specific English words may have two or more recognized spelling forms, Juan. The British way or the American way. Canada has adopted the British way.
One notable example is the word center. Canadians and Brits prefer to spell it as centre. When I typed in "center" to search the on-line Merriam Webster dictionary I got 16 hits. I only got two hits when I typed "centre". So looks like the British (and Canadian)way is not the common way.
I don't fully agree with this. Canadian spelling is not identical to British spelling. They'd spell programme except if it's a computer programme, in which case program is acceptable. In Canadian English, the two are totally interchangeable.
Likewise, whereas British English accepts both the -ize and -ise spellings and their derivatives for the causative suffix, as long as it is used consistently throughout the article or publication, Canadian English never uses the -ise spelling for this particular suffix.
There are other differences too, but this should be enough to show you that spelling rules do vary between British and Canadian English, as they do between Canadian and US English. Australian English is different too. For instance, while Australians usually use the -our derivative in words such as colour, etc., they do make an exception for labor, spelt without the u.
This is one reason English spelling drives non-native English-speakers nuts.