The two main dialects of English, British and American, have a number of differences between them. This also extends to pronunciation. The following discusses the main differences in pronunciation between Received Pronunciation and General American.
In General American, the /r/ is pronounced at the end of a syllable. In Received Pronunciation, however, it is either not pronounced as in car or a schwa is produced instead as in here.
Most speakers of General American make no distinction between father and bother. They pronounce both words with the same vowel. However, in Received Pronunciation, they are pronounced with different vowels.
The vowel of words such as coat is different in General American and Received Pronunciation. In General American it tends to have a shorter duration and the vowel is articulated farther back than in Received Pronunciation. The General American vowel can be a monophthong, but in Received Pronunciation it's always a diphthong.
Flapping is very common in General American. It occurs intervocalically in words such as bottle, city, and ladder. The result is that the words medal and metal sound the same in General American, but they are distinguished in Received Pronunciation.
Yod-dropping is also common in American English. Many Americans make no distinction between do and dew. However, speakers of Received Pronunciation do. In the word stew, American speakers always apply yod-dropping, but Received Pronunciation speakers don't.
The trap-bath split doesn't exist in General American. Speakers of General American pronounce can and can't with the same vowel. Speakers of Received Pronunciation don't. In General American, words such as dance, fast and laugh have a front vowel while in Received Pronunciation they have a back vowel.
General American and Received Pronunciation exhibit a number of differences in pronunciation. These include syllable-final /r/, the trap-bath split, flapping and yod-dropping. The trap-bath split and lack of syllable-final /r/ in Received Pronunciation are relatively recent developments which weren't adapted by General American.