I'm British, and as far as I can see, there isn't a massive difference between American English and British English. They do spell some things differently (we spell colour as 'colour' they spell it as 'color'), they pronounce some things differently (like they pronounce tomatoes as 'toh-may-toes' instead of 'toh-mah-toes') and they have some different words for things (pavement/sidewalk, chocolate/candy, petrol/gas), but other than that, it's mostly the same. Oh, remembered another thing; American English misses out some parts of the sentence that we normally keep in, for example; British; I fell out of the window. American; I fell out the window. And lastly, British English isn't actually that formal. If you watch programmes where all the British people speak like the Queen then yeah, of course it's formal, but very few of us are actually that posh. I hope this makes some sense, because I have a habit of not making sense to other people :S

English is English, and most of us can understand each other without too many problems. I believe that English as spoken by an educated American, and English as spoken by an educated Brit, are very similar. Of course there are some vocabulary differences, and some grammatical differences (such as use of "got/have", American preference for past simple where British use present perfect, etc), but generally the standard and quality of English - especially at an academic level - are very similar in both countries. The differences occur in more informal settings, amongst the uneducated, or in rural areas or amongst certain ethnic groups. For example, a black man from a rough neighbourhood in New York is going to speak entirely differently to a working class white man from York (that's the original York, in England). British English may be perceived by some as being more formal because American English has become somewhat simplified over time, and also because British English is probably richer and more varied as a whole. We British also tend to carry ourselves a bit more formally, or at least some of our most well-known film exports do (James Bond, all of Hugh Grant's characters, etc), and this no doubt emboldens this idea. The image of the "British Gentleman" is almost legendary throughout much of the world, and this may help to reinforce misconceptions. But to answer the question, is the grammar more complex in British English? No. Do more Americans than British speak bad English? As a percentage, probably no. Are we more likely to see poor English on an American TV show than on a British one? Perhaps, but then again there are more American shows than British being pumped around the world.

我认为是发音不一样 （tomatoes, vitamin, Z 英国是zed的声音美国是zee的声音）。。。有时候我遇到不一样的语法。。比如说：英国的英文：I have terrible toothache. 但是美国英文： I have a terrible toothache.

In fact, I have the same observations and I saw a lot of questions on the same subject but what matters to me what is the opinion of British English speakers on this topic?

For me as for learner American English seems to be carrying out the brain:) I mean American spoken language and made such a conclusion after watching American films. Especially sticks out the abundance of different idiomatic expressions which are usually constructed of simple words like "get", "go", "step" and so on. For example, "to chicken out" means to be afraid of something. May be, I'm not right, and the European English also has such features as well...