http://learnenglish.britishcouncil.org/en/grammar-reference/british-english-and-american-english
British English and American English
British people and American people can always understand each other – but there are a few notable differences between British English and American English
Grammar
Americans use the present perfect tense less than speakers of British English and a British teacher might mark wrong some things that an American teacher would say are correct.
- US Did you do your homework yet?
- Brit. Have you done your homework yet?
- US I already ate.
- Brit. I’ve already eaten.
In British English, ‘have got’ is often used for the possessive sense of ‘have’ and ‘have got to’ is informally used for ‘have to’. This is much less common in American English.
- Brit. I’ve got two sisters.
- US I have two sisters.
- Brit. I’ve got to go now.
- US I have to go now.
There are a number of other minor grammatical differences.
Vocabulary
There are a lot of examples of different words being used in British and American English. Here are a few of the commonest.
- angry (Brit.) = mad (US)
- autumn = fall
- boot (of a car) = trunk
- chemist’s = drug store
- cupboard = closet
- flat = apartment
- lift = elevator
- nappy = diaper
- pavement = sidewalk
- petrol = gas/gasoline
- rubbish = trash
- tap = faucet
- trousers = pants
There are British words which many Americans will not understand and vice versa. There are also words which exist in both British and American English but have very different meanings.
Spelling
There are also a number of different spelling rules between British English and American English.
1 Some words that end in ‘-tre’ in British English end in ‘-ter’ in American English.
- US theater, center
- Brit. theatre, centre
2 Some words that end in ‘-our’ in British English end in ‘-or’ in American English.
- US color, labor
- Brit. colour, labour
3 Some words are shorter in American English than in British English.
- US catalog, program
- Brit. catalogue, programme
There are other minor spelling differences between British and American English.