Generally speaking, most English words are spelt the same in American and British English. However, there are some notable spelling differences.
Listed below are just some examples of spelling differences you may encounter:
-our (British) vs. -or (American)
- Examples: colour vs. color, armour vs. armor, flavour vs. flavor
-ise or -ize (British) vs. only -ize (American)
- Examples: apologise vs. apologize, fantasise vs. fantasize, idolise vs. idolize
-yse (British) vs. –yze (American)
- Examples: analyse vs. analyze, paralyse vs. paralyze
Doubling the L in a verb conjugation (British) vs. keeping the single L (American)
- Examples:travelled vs. traveled, labelling vs. labeling
AE (British) vs. E (American)
- Examples:leukaemia vs. leukemia, paediatrics vs. pediatrics
-ence (British) vs. -ense (American)
- Examples: defence vs. defense, licence vs. license
only -ogue (British) vs. -og or -ogue (American)
- Examples:catalogue vs. catalog, dialogue vs. dialog
-re (British) vs. -er (American)
- Examples:metre vs. meter, centre vs. center
-t (British) vs. -ed (American)
- Examples:burnt vs. burned, dreamt vs. dreamed, leapt vs. leaped
In addition, some specific words are spelt differently in American and British English. Some examples include airplane (American) and aeroplane (British), gray (American) and grey (British), and tire (American) and tyre (British).
(Grant)