Supper or Dinner?

I was listening to something yesterday and the question was - is it Supper or Dinner? (And all you Brits - this does not include "Tea" - cause NO ONE has been able to intelligently explain to me exactly what TEA" really is!) I mean - does it depend on the quality of what you are eating that defines whether or not it's Dinner or Supper. Like if you're having KD - would that be Dinner? Cordon Bleu - Supper? Eastern Canada or Western Canada? I mean - I can't go by what MY brain tells me to use - cause I use them both - come on - help me out here - this is just one more thing that has me confused.............my brain can take no more.................DIZ!