Dear Mr. B:

You wrote:
Would you give me a list of all the British words that have spelling differences between American English?

Here are some examples;
endeavour, colour, programme, etc.

thank you much

I am not sure that anyone outside of a lexicographer could do that with any sort of guarantee, especially when you start to include scientific terms (e.g., aluminum vs. aluminium). Most of the common words and the common patterns (you note above -or vs. -our at the end of impersonal nouns) can be found at https://englishplus.com/grammar/00000186.htm .

It might be possible to make a fairly exhuastive list by using a full featured word processor which has both English and American spell checkers, such as Grammar Slammer Deluxe with Checkers. Load one of the dictionaries as a document, if possible, and then run the other spell checker to check it. Any flagged words would give you pretty good list.

I hope this helps.