Why does a difference in spelling exist between British and American English?

I understand that the use of different terms for the same item (e.g., "car park" vs. "parking lot") has already been discussed, but I'm interested to know why we spell the same words differently in the UK.

Obvious examples include:

• favourite and favorite
• cancelled and canceled
• dialogue and dialog
• honouring and honoring
• behaviour and behavior

My guess would be that this has something to do with British spellings preserving their Latin roots more strongly than the American equivalents, but I don't know. I'd also like to know why present and past tense variations are derived in different ways too, as in the derivatives of "cancel" above.

Solution 1:

In the late 1700's, English spelling wasn't really well standardized. In the early 1800's, America and Great Britain standardized their spellings separately. American spellings were heavily influenced by Noah Webster's dictionary, first published in 1828. He simplified the spellings of many words, and those simplified spellings became standard American English.