Spelling in New Zealand

If when we come home we spell things a little different it is because some words are spelled differently here.  For example see if you know what the following words are:  tyre, labour, colour, centre, favourite, metre, authorise, realise, vitalise, enrolment, enrol, practise, harbour, programme, neighbour, artefacts, organisation, maximise.  After seeing these words all the time we sometimes questions how a word is actually spelled.  Now we have a reason to misspell words.