• Americanization
• Briticism
• British Spelling
• Estuary English
• H-Dropping
• Irish English
• Received Pronunciation
• Scottish English
• Standard British English
• Welsh English

Examples and Observations

• "The phrase British English has . . . a monolithic quality, as if it offers a single clear-cut variety as a fact of life (alongside providing a brand name for language-teaching purposes). It shares, however, all the ambiguities and tensions in the word British, and as a result can be used and interpreted in two ways, more broadly and more narrowly, within a range of blurring and ambiguity."
  (Tom McCarthur, The Oxford Guide to World English. Oxford University Press, 2002)
• "Before English speakers began to spread around the world, first in large numbers in America, there was no British English. There was only English. Concepts like 'American English' and 'British English' are defined by comparison. They are relative concepts like 'brother' and 'sister.'"
  (John Algeo, preface to The Cambridge History of the English Language: English in North America. Cambridge University Press, 2001)

• American Influence on British Grammar
  "Whereas in popular perception, particularly in Britain, there is often fear of a blanket 'Americanization' of British English, our analyses will show that documenting the true extent of the grammatical influence of American English on British English is a complex business. . . . There are a few limited instances of presumably direct American influence on British usage, as in the area of the 'mandative' subjunctive (e.g. we request that this be made public). But the most common constellation by far is that American English reveals itself to be slightly more advanced in shared historical developments, many of which were presumably set in motion in the Early Modern English period, before the streams of British and American English parted."
  (Geoffrey Leech, Marianne Hundt, Christian Mair, and Nicholas Smith, Change in Contemporary English: A Grammatical Study. Cambridge University Press, 2012)
• Vocabulary of British English and American English
  "Proof that English in America very quickly became distinct from British English is found in the fact that, as early as 1735, British people were complaining about American words and word usages, such as the use of bluff to refer to a bank or cliff. In fact, the term 'Americanism' was coined in the 1780s to refer to particular terms and phrases that were coming to characterize English in the early US but not British English."
  (Walt Wolfram and Natalie Schilling-Estes, American English: Dialects and Variation, 2nd ed. Blackwell, 2006)
  
  "A writer in the London Daily Mail complained that an English person would find 'positively incomprehensible' the American words commuter, rare (as applied to underdone meat), intern, tuxedo, truck, farming, realtor, mean (nasty), dumb (stupid), enlisted man, seafood, living room, dirt road, and mortician, although some of these have since become normal in British English. It is always unsafe to say what American words a British person will not understand, and there are some pairs [of words] that would be generally 'comprehended' on both sides of the Atlantic. Some words have a deceptive familiarity. Lumber with Americans is timber but in Britain is discarded furniture and the like. Laundry in America is not only the place where clothing and linen are washed but the articles themselves. A lobbyist in England is a parliamentary reporter, not one who attempts to influence the legislative process, and a pressman for Americans is not a reporter but one who works in the pressroom where a newspaper is printed.
  
  "It is of course on the level of more colloquial or popular speech that the greatest differences are noted."
  (Albert C. Baugh and Thomas Cable, A History of the English Language, 5th ed. Routledge, 2002)
  
  "Most people know that when a British schoolteacher asks his pupils to take out their rubbers, he is inviting them to produce their erasers, not about to give them a lesson in contraception. British people who live in flats do not set up home in burst tires. The word 'bum' in British English means buttocks as well as vagrant.
  
  "People in Britain do not usually say 'I appreciate it,' have a hard time, zero in, reach out to other people, stay focused, ask to be given a break, refer to the bottom line or get blown away. The word 'scary,' as opposed to 'frightening' or 'alarming, sounds childish to British ears, rather like talking about your buttocks as your bottie. Brits tend not to use the word 'awesome,' a term which, if it were banned in the States, would cause airplanes to fall from the sky and cars to lurch off freeways."
  (Terry Eagleton, "Sorry, but Do You Speak English?" The Wall Street Journal, June 22-23, 2013)
• British English Accents
  "Sensitivity about accents is everywhere, but the situation in Britain has always attracted special interest. This is chiefly because there is more regional accent variation in Britain, relative to the size and population of the country, than in any other part of the English-speaking world--a natural result of 1,500 years of accent diversification in an environment which was both highly stratified and (through the Celtic languages) indigenously multilingual. George Bernard Shaw was exaggerating when he had phonetician Henry Higgins say (in Pygmalion) that he could 'place a man within six miles. I can place him within two miles in London. Sometimes within two streets'--but only a little.
  
  "Two major changes have affected English accents in Britain over the past few decades. The attitude of people towards accents has altered in ways that were unpredictable thirty years ago; and some accents have changed their phonetic character very significantly over the same period."
  (David Crystal, "Language Developments in British English." The Cambridge Companion to Modern British Culture, ed. by Michael Higgins et al. Cambridge University Press, 2010)
• The Lighter Side of British English (From an American Perspective)
  "England is a very popular foreign country to visit because the people there speak English. Usually, however, when they get to the crucial part of a sentence they'll use words that they made up, such as scone and ironmonger. As a sophisticated traveler, you should learn some British words so you can avoid communications mixups, as is shown by these examples:

  Example 1: The Unsophisticated Traveler
  English Waiter: May I help you?
  Traveler: I'd like an inedible roll, please.
  English Waiter (confused): Huh?
  
  Example 2: The Sophisticated Traveler
  English Waiter: May I help you?
  Traveler: I'd like an ironmonger, please.
  English Waiter: Coming right up!"

  (Dave Barry, Dave Barry's Only Travel Guide You'll Ever Need. Ballantine Books, 1991)