There are many differences between US and UK english. To quantify some of the differences, and the situation in other english-speaking countries, I used Google to determine the ratios of the frequencies of various synonyms which distinguish the languages.
| UK | Australia | Canada | |
| burgled / burglarized | 65 | 16 | 0.6 |
| colour / color | 5 | 0.9 | 1.6 |
| pavement / sidewalk | 11 | 4.1 | 0.8 |
| theatre / theater | 6.1 | 6.8 | 3.2 |
| aluminium / aluminum | 1.6 | 9.7 | 0.3 |
| tv aerial / tv antenna | 6.3 | 0.046 | 0.1 |
The burgled / burglarized pair is the most polarised result, with the former used 65 times more often in UK websites than the latter. In Canada, on the other hand, burgled is used only just about half as often as burglarized.
The aluminium / aluminum result is odd. The large amount of aluminium mining occurring in Australia leads to both forms being most common there in terms of total usage. However, the UK version is almost 10 times more popular in Australia than the US version, whereas in the UK it's less than twice as popular. I don't know a good reason for that.
Another odd result is that color is more popular than colour in Australia. Children are taught colour at school, and I know of nobody who uses color. However, for foreign companies it seems to be a word that they just don't bother adjusting to the native spelling.
The biggest disparities in the UK are where it's a different word, rather than just an alternative spelling. You'd expect culture to preserve these with more vigour.
I'm also struck by how in Australia the US term tv antenna is 21 times more popular than its UK equivalent tv aerial, for which I have no explanation.
Addendum: I am contemplating writing a tool to automatically query Google for these statistics. Stay tuned.