Has the UK's english so many differences from the American english? For me, when I listen the Britishers talking, it is easier to understand, even I watch a lot of American shows and listen to American musics. So, the UK's is really more clear? When Britishers​ listen Americans, have they any problems​ with it?

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The UK accent can be easier to understand, particularly if it is someone from the south of England speaking :) But there are lots of different British accents and that includes Welsh and Scottish, UK accents would also include Northern Irish accent! But the main accent that would be on television and in films is the southern English general accent. American accents are very easy to understand for the British, but this could be because we would be used to hearing them and understand the language well enough that we can understand what they are saying more easily than if we were learning English :)

Just to let you know, when you are talking about people from Britain you can either say "Brits" or "the British", not Britishers :)