http://www2.gsu.edu/~wwwesl/egw/jones/differences.htm

Spelling differences between American and British English

 

-or vs. -ourAmerican British

color colourfavorite favouritehonor honour

-ll vs. -lAmerican British

enrollment enrolmentfulfill fulfilskillful skilful

-og vs. -ogueAmerican British

analog analoguecatalog cataloguedialog dialogue

-ck or -k vs. -queAmerican British

bank banquecheck chequechecker chequer

 

-ense vs. -enzeAmerican British

defense defencelicense licence

 

-ze vs. -seAmerican British

analyze analysecriticize criticisememorize memorise

-er vs. -reAmerican British

center centremeter metretheater theatre

-e vs. -oe or -aeAmerican British

encylopediaencylycopaedia

maneuver manoeuvremedieval mediaeval

-dg vs. -dge (or -g vs. -gu)

American Britishaging ageingargument arguementjudgment judgement

 

Other

American Britishjewelry jewellerydraft draughtpajamas pyjamas plow ploughprogram programmetire tyre

In British English, words that end in -l preceded by a vowel usually double the -l when a suffix is added, while in American English the letter is not doubled.  The letter will double in the stress is on the second syllable.

Base Word American Britishcounsel counseling counsellingequal equaling equallingmodel modeling modellingquarrel  quarreling quarrellingsignal signaling signallingtravel traveling travellingexcel excelling excellingpropel propelling propelling

Spelling of verbs

This is related to formation of the past participle for verbs. For a complete list of irregular verb spellings, see Susan Jones' Complete List of English Irregular Verbs at this web site.  Below is a sampling of the three main categories of differeneces with verbs.

-ed vs. -t

The first category involves verbs that use -ed or -t for the simple past and past participle.   Generally, the rule is that if there is a verb form with -ed, American English will use it, and if there is a form with -t, British English uses it.  However, these forms do not exist for every verb and there is variation.  For example, both American and British English would use the word 'worked' for the past form of 'to work', and in American English it is common to hear the word 'knelt' as the past tense of 'to kneel'.

Base form American Britishto dream dreamed dreamtto leap leaped leaptto learn learned learnt

base form vs. -ed

The second category of difference includes verbs that use either the base form of the verb or the -ed ending for the simple past.

Base form American Britishto fit fit fittedto forecast forecast forecastedto wed wed wedded

irregular vs. -ed

The third category of difference includes verbs that have either an irregular spelling or the -ed ending for the simple past.

Base form American Britishto knit knit knittedto light lit lightedto strive strove strived

So what does tall his mean for learners of English?  In the beginning, unfortunately, it means a lot of memorization (or memorisation) and of course, a few mistakes.  For spoken English, the differences are barely audible, so forge ahead and don't be too concerned with whether a word is spelled 'dwelled' or 'dwelt'.  With written English, however, if you are unsure about the spelling, better to ask your teacher or look the word up in the dictionary and see what the experts say.

http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences

http://www.englishclub.com/writing/spelling_american-english.htm#

English and American English Spelling

Here are the principal differences in spelling between English and American English.

English American English

Final -l is always doubled after one vowel in stressed and unstressed syllables in English but usually only in stressed syllables in American English, for example:

rebel > rebelledtravel > travelled

rebel > rebelledtravel > traveled

Some words end in -tre in English and -ter in American English, for example:

centretheatre

centertheater

Some words end in -ogue in English and -og in American English, for example:

analoguecatalogue

analogcatalog

Some words end in -our in English and -or in American English, for example:

colourlabour

colorlabor

Some verbs end in -ize or -ise in English but only in -ize in American English, for example:

realise, realizeharmonise, harmonize

realizeharmonize

Common Differences

English American English

all right all right, alright (disputed)

analyse analyze

centre center

cheque check

colour color

counsellor counselor

criticise, criticize criticize

defence defense

doughnut donut

favour favor

fibre fiber

flavour flavor

fulfil fulfill

grey gray

honour honor

humour humor

jewellery jewellery, jewelry

judgement, judgment judgment

kerb curb

labour labor

license, licence (verb)licence (noun)

license (verb)license (noun)

litre liter

metre meter

mould mold

neighbour neighbor

offence offense

practise (verb)practice (noun)

practice (verb)practice (noun)

pretence pretense

programme program

pyjamas pajamas

realise, realize realize

savour savor

speciality specialty

theatre theater

travelledtravelling

travelled, traveledtravelling, traveling

tyre tire

valour valor

Dictionary with Canadian, British and American spelling differences:

http://www.lukemastin.com/testing/spelling/cgi-bin/database.cgi?action=home