<human>:  What are the regional differences between American and British English?
<bot>: American English and British English have a few regional differences, including vocabulary, grammar, and pronunciation. American English typically has more informal language and may use certain words and phrases that are not heard in British English. Grammatically, American English often uses fewer articles and abbreviations compared to British English. Pronunciation-wise, American English is said to have looser, more relaxed rhythms and a more open vowel sound than British English.