Then, of course, we have the issue of regional spelling and word usage. The Americans claim that they speak/read/write English: yet for them the vowel 'u' seems to have a sharply diminished role: color, neighbor, favor, labor, etc etc. As most spell-checks are set to American-English defaults (unless one fiddles with them on installation) this means that the youth of such countries as Australia, Canada, New Zealand and South Africa is increasingly 'Americanising' their spelling. The use of the word 'Mom' instead of 'Mum' is such an example.
Then there's different meanings of common words - an American asking for a 'rubber' in Boots the Chemist would be given strange looks; as would an Englishman asking for the same thing in Office World.
All very interesting!!
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Happiness is a warm L1011