system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why the English language changes around the World.

Dropping the "U" from colour as an example. Substituting a "Z" for an "S". Reversing the "E" and "R" in certain words. For example litre an liter.

Why did these changes occur in various different English speaking countries?
gpt
Most of these are just American/British English differences.

There were no English dictionaries until the 19th century. By then, Americans had taken to spelling things a certain way and the British had their own opinion. By the time Oxford and Webster formalized the spellings with a dictionary, there were quite a number of differences. Popular attitudes in England at the time favored the more Frenchy spellings like colour, realise and litre.

As for the rest of the world, it's largely about who was a greater influence. Former British colonies tend to be taught British English and places with greater American influence tend to be taught American English.