Over time I have noted many of the differences and have also gleaned more from other sources. Over the next few days I plan to publish a catalogue of these variants.
The initial list shows differences between American and British spelling of common words. An asterisk indicates that the pronunciation differs as well as the spelling. A plus sign indicates a British usage that is, apparently, not unknown in North America.
American | British | Notes |
aluminum * | aluminium | Note the i has been dropped in the AE version. |
analog | analogue | |
anesthesia | anaesthesia | |
archeology | archaeology | |
boro | borough | "boro" is informal and is sometimes seen in British road markings. In |
bylaw | bye law | |
catalog | catalogue + | |
center | centre | |
color | colour | |
curb | kerb | Edge of roadway or pavement. "curb" in the sense of "restrain" is used in British and American English. |
defense | defence | |
dialog | dialogue + | |
donut | doughnut | "donut" is informal and is quite commonly used in BE to suggest that the bun is of a typical American character. |
draft | draught | |
encyclopedia | encyclopaedia | |
favorite | favourite | |
gage | gauge + | American usage is obsolete |
gray | grey + | |
gynecology | gynaecology | |
hauler | haulier | |
honor | honour | |
humor | humour | |
jewelry | jewellery | |
license | licence | British usage is license for the verb and licence for the noun |
maneuver | manoeuvre | |
meter | metre | British usage is "meter" for a measuring device and "metre" for the unit of length. It has been noted that the |
mold | mould | |
mustache | moustache + | |
nite | night | "nite" is informal in both AE and BE. |
omelet | omelette + | |
pajamas | pyjamas | |
practice | practise | British usage is "practise" for the verb and "practice" for the noun |
program | programme | British usage is "program" for computers and "programme" for television or radio. |
routing | routeing | |
specialty | speciality | |
story | storey | of building |
sulfur | sulphur + | |
thru | through + | American usage is obsolescent but may still be seen on road signs etc., |
tire | tyre | part of wheel in contact with road |
vise | vice | tool |
Generally American English -or as a word ending is equivalent to -our in British English, American -er as a word ending is sometimes equivalent to -re in British English. In American English the final e is removed from verbs before adding -ing, in correct British English this is not done giving "routeing" (British) and "routing" (American). If a verb ends in a single 'l' then the American -ing, -ed and -er forms also have a single 'l' whereas the British forms have a double 'll'. For example American English has signaler, signaling and signaled whereas British English has signaller, signalling and signalled. American English tends to prefer -ize and -ization whereas British English prefers -ise and -isation contrary to statements by certain well-known British authorities and much spell checking software.
Canadian spelling seems to be intermediate between the British and American (US) forms but is generally closer to British practice. There are variations from province to province. A quiet half-hour spent perusing the Vancouver Yellow Pages suggested that "aluminium", "gauge", "jewellery" and "mould" are preferred. [OK - I know there are better things to do in Vancouver !]. Some people have suggested that Canadians normally use "aluminum".
There are, of course, exceptions to the above rules. American usage is "glamour" not "glamor" and "advertising" not "advertizing". British usage has "honorary" and "honorific" without the "u". Several sources have also noted that the British usages "centre" and "theatre" are displacing the American usages, particularly where the establishment in question wants to suggest that it is of superior quality.
When spelling out words (and 'phone numbers) it is British practice to say things such as "double e" for "ee" and "treble 3" for "333".
Please note that "tonne" is not a British spelling of "ton" but a quite separate metric unit equal to 1000 kg as distinct from the British ton of 2240 lbs (= 1016.96 kg).