Answer: One of the biggest differences comes with words ending in ‘-ise’. American English changes pretty much all of these to ‘-ize’ – ‘organize’, ‘recognize’, and so on. They do the same thing with ‘-yse’ (‘analyze’, ‘paralyze’). Most words ending in ‘-our’ in British English end in ‘-or’ in American English (color, flavor, honor, neighbor, rumor, labor, humor). Except for ‘contour’, ‘velour’, ‘paramour’ and ‘troubadour’ which are spelt the same everywhere. We don’t know why. Although Neil might. (In the olden days we used to put ‘u’s in fairly unusual places in British English like ‘ambassadour’, ‘governour’, ‘inferiour’, ‘errour’, ‘horrour’ and ‘mirrour’. True.) Americans also sometimes like to swap around ‘r’s and ‘e’s. So ‘centre’ becomes ‘center’. Same goes for ‘kilometer’, ‘theater’, ‘caliber’, ‘fiber’, ‘saber’ and ‘somber’. We also disagree on words ending in ‘-ce’. Although we both use ‘advice’ as a noun and ‘advise’ as a verb, American English has abandoned the ‘licence’/‘license’ and ‘practice’/‘practise’ distinction (we’re hanging on to it) and uses ‘practice’ and ‘license’ for both meanings (see Tricky words). American English uses ‘defense’ and ‘offense’, while we write ‘defence’ and ‘offence’. ‘Defensive’ and ‘offensive’ always have an ‘s’. And words written with ‘ae’/‘oe’ in British English have a single ‘e’ in American English, like ‘amoeba’, ‘anaemia’, ‘anaesthesia’, ‘foetal’, ‘haemophilia’, ‘oesophagus’, ‘orthopaedic’ and ‘paediatric’. All lovely words, we’re sure you’ll agree. Americans are happy with Oxford commas (that’s when you put a comma before the ‘and’ in a list – see Commas). They also prefer double quotation marks (see Quote marks). And finally, Americans tend to treat brands, for example Apple, and collective nouns like ‘team’ or ‘staff’ as single units. So they use them with the singular verb (unless you’re definitely talking about individuals). So in America you’re more likely to hear ‘Apple changed its logo’ than ‘Apple changed their logo’. For Brits, it’s the opposite.