For all practical, non-snob, non-competition purposes? Nothing.
But essentially, you could put it in 1911 terms: An average production CZ (or Tanfoglio) is like $400-600 and is like a bog-standard American 1911. A Canik or Sarsilmaz is even cheaper and is kinda like a Rock Island piece- maybe a few little niggles to it, but overall pretty damn similar. Arguably higher value.
But when you start to get into the $900-1000+ range, you expect parts of the best quality, hand fitting, ect. And that's the Sphinx.
Compare the one pictured to something like this:
http://cz-usa.com/product/cz-compac...-heinie-night-sights-14-rd-mags-by-cz-custom/
And they make Sphinx 3000's to rival the $3000 Czechmate.
It's another similarity to 1911's that while Colt and Springfield will sell you one HELL of a 1911, there's generally better for cheaper. Personally I think someone would have to be nuts to buy any of the higher-end CZ custom shop guns.