A number of words and meanings that originated in Middle English or Early Modern English and that always have been in everyday use in the United States dropped out in most varieties of British English; some of these have cognates in Lowland Scots. Terms such as fall ("autumn"), pavement (to mean "road surface", where in Britain, as in Philadelphia, it is the equivalent of "sidewalk"), faucet, diaper, candy, skillet, eyeglasses, crib (for a baby), obligate, and raise a child are often regarded as Americanisms. Gotten (past participle of get) is often considered to be an Americanism, although there are some areas of Britain, such as Lancashire and Yorkshire, that still continue to use it and sometimes also use putten as the past participle for put.
Other words and meanings, to various extents, were brought back to Britain, especially in the second half of the 20th century; these include hire ("to employ"), quit ("to stop," which spawned quitter in the U.S.), I guess (famously criticized by H. W. Fowler), baggage, hit (a place), and the adverbs overly and presently ("currently"). Some of these, for example monkey wrench and wastebasket, originated in 19th-century Britain.
The mandative subjunctive (as in "the City Attorney suggested that the case not be closed") is livelier in AmE than it is in British English; it appears in some areas as a spoken usage, and is considered obligatory in contexts that are more formal. The adjectives mad meaning "angry", smart meaning "intelligent", and sick meaning "ill" are also more frequent in American than British English.
http://en.wikipedia.org/wiki/American_English#English_words_that_survived_in_the_United_States