There are some well-known spelling differences between British English and American English. Many of these spelling differences result from French influence on English. British English has a tendency to keep the spelling of many words of French origin. Americans try to spell words more closely to the way they sound phonetically and they tend to omit some letters.

The general spelling differences between British and American English are listed below.

British -our vs. American -or 

British -re vs. American -er
difference

British -ise vs. American -ize
difference

British -ll vs. American -l
difference

British -ae vs. American -e
difference

British -ogue vs. American
-og difference

British –ce vs. American
-se difference

It is useful to learn both British and American English forms, but a good recommendation is to aim for consistency in your spelling.