(Ok, well I'm going to be talking in Canadian English)
1. Many people get the words, center and centre mixed up (along with metre, centimetre, kilometre and more). But in Canada, the 'er' are switched around making it 're'
EX. I am over one metre tall.
2. People get the words, colour and color mixed up as well. In Canada (and probably in Britain), we have the original wording as, colour. This is also in the words, labour, neighbour & flavour
3. 'You're' stands for you are while the word 'your' means subject's (usually a direct subject, you) possession.
4. Along with they're means, they are (EX. They're [they are] talking so much during class). There means a place (EX. Over there!) and their means of an indirect subject's possession (EX. You have to give back their pen).
That's all I have for now!
