There’s hardly any difference at all between British and American English. The main difference is phonological (the way the language is spoken). Differences in vocabulary and spelling are very limited and there are hardly any differences at all in structure. Of course, for adults, the range of reference can vary between BrE and AmE. British English has a European range of reference. AmE and AusE similarly reflect the references of the geographical locations. This is one reason why AmE and AusE are so important in SE Asia.
English is a world language. People are learning it worldwide because they have the expectation that they will be able to use the language they have learned in any part of the world. The dominance of English has historical reasons relating back to the British Empire, but its widespread use today is largely due to American influence worldwide. Here are some reasons why people learn English:
－political: English may be a neutral means of communication between different language groups in a large country: e.g. India.
－economic: English is the language of trade, business and tourism.
－practical: English is the language used by air traffic controllers, in academic conferences, etc.
－scientific and technical: most scien