Without sending you to a wikipedia page, here's a suggestion: try to find out the origin of any audio or movie/TV series you watch. So if it was a movie made in the UK, you may assume the speaking style is British (normally). Listen carefully to how they pronounce and phrase their sentences, even if you don't follow every single word. Listen and watch widely, both US and UK media. But always do a little research first, so you are "ready" for US/UK speech. Notice the differences - it'll get easier the more you watch! To refine it further, if you can find someone who can point out the regional accents, that would also help. Eg. a US film may be set in California, but have a character from New York or even Canada. Listen for those differences also. You've asked a big question. Differences in US/UK pronunciation can be frequent and many. And that doesn't even consider other English-speaking countries (like mine), also with different pronunciation.

American English is quite "slangy"

英國人發音有很多是不捲舌的 感覺英國人舌頭較短 像是公園park 英國人的r是不捲舌的 還有英國人說apple 的a 發音不像美國人那麼明顯,好比美國人說(ㄚ婆) 英國人就會說(ㄟ婆) 大致來說,美國人說話比較誇張,重捲舌音,說話比較隨性,常常縮寫一句話 像是i am going to ... 美國人就會說 i am gonna .... 英國人說話就比較紳士,文雅一些 推薦你去多看一些英國的電影 像是大家耳熟能詳的"哈利波特", "k歌情人" k歌情人是由"休葛蘭"演的,他是一個英國人,本身也演過很多部電影, 還有BJ單身日記,同床異夢....... 不過我想很多台灣的電影名稱和中國的不一樣,你就參考看看八 還有多聽廣播ICRT和BBC news 會對英國腔的了解有更大幫助:D

this very question arises here every 2 or 3 days look at the previous questions - - - is very rude ^__^

Ha what a question, feel them yourself, huh? Movies maybe.