So being the loser that I am, I've watched most of the different Real Housewives series. And the thing that REALLY sets them apart from TOWIE and MIC is that they're all so much more natural! Obviously some of it is set up as well but there's a difference - they all actually seem to meet up/socialise/argue in a much more organic way.
TOWIE and MIC, while still authentic to a degree and still having real arguments/chat, are way more awkward and staged. Maybe the Americans are just better actors?