One of the largest differences between UK and US English is simply a cosmetic one: spelling. Here are 9 of the most common spelling variations between UK and US English.
1) UK -our = US -or
Examples: colour/color, humour/humor, flavour/flavor, favourite/favorite
2) UK -re = US -er
Examples: centre/center, metre/meter, litre/liter
3) UK -ise = US -ize
Examples: realise/realize, organise/organize, recognise/recognize
4) UK -que = US -ck
Examples: cheque/check, chequered/checkered
5) UK -ll before -ing = US -l before -ing
Examples: travelling/traveling, signalling/signaling
6) UK -l = US -ll
Examples: appal/appall, enrol/enroll
7) UK -ce = US -se
Examples: licence/license (noun form), defence/defense
An exeption to the rule: UK practise (verb) and practice (noun) = US practice (both verb and noun).
8) UK -ogue = US -og
Examples: catalogue/catalog, dialogue/dialog, epilogue/epilog
9) UK -t =US -ed (in a select group of past tense verbs)
Examples: spelt/spelled, dreamt/dreamed, burnt/burned, spoilt/spoiled
Have you gotten into trouble with other spelling variations not included here? Let me know by leaving your comments!