As an online teacher of English this question comes up quite a bit. There are in fact quite a few differences between British and American English only they are not as apparent since they are both 'English'. I will give you a few examples which I explain to my students:
1. have you got? (British) vs do you have? (American)
2. on the week end(American,Canadian) vs at the weekend(British)
3. outght not (strictly British) should not (typically American, Canadian)
Regards,
Steve-Online English Teacher
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