As for the difference? The difference is not too big. It sounds like American English feels clearer and rounder, and its mouth will open wider when it is pronounced.
British English sounds like it. I feel that I pronounce it at the bottom of my throat, and my mouth will be smaller. American English is very good and easy to understand.
The differences between Britain and America in oral pronunciation are very obvious. Geographical separation is the reason for this difference. Since the colonists arrived in North America, their pronunciation of words has been different from that of Britain. This differentiation is a normal phenomenon. Because the direct contact between the residents of the two places is limited to words and other printed materials, there is less direct dialogue.
An important difference between American English and British English is that the letters A and R are pronounced differently ... such as fast, path and half, which are pronounced in British English as in father, not in man. In British English, the letter R is silent except for vowels. Therefore, in British English, lord is pronounced land. Also, in American English, the pronunciation of weak syllables should be clear. For example, secretaries and necessities have four syllables in American English and only three syllables in British English.
There are historical reasons for this difference in pronunciation. When the early colonists left Britain in the17th century, the letters A and R were pronounced the same as American English today. However, in the late18th century, southern dialects appeared as British standard English, while American English did not change like British English, resulting in different pronunciations between the two countries.
From a linguistic point of view, Canadian English can be regarded as a dialect of American English (just as Dutch can be regarded as a German dialect). But don't tell this to Canadians: Canadians hate being told that they are the same as Americans. Canadians always try their best to protect their culture from being assimilated by America, a powerful neighbor in the south. Most Australian accents are similar to British accents, but Australians pronounce [ei] as [ai], that is, even their most commonly used word mate is pronounced as [mait] (like may). Australian English and British English are not only different in pronunciation, but also in the meaning and expression of words, because British English has changed many times ~ and Australian English has basically not changed, which means that Australian English now is very similar to British English hundreds of years ago.