One has wood trim the other a sort of carbon effect,look at the DB options brochure its massive.A statement by DB said that other than fleet cars there were not two e class motors ordered exactly the same.
I don't know if other folk are the same, but when I was toying with the idea of both a Merc and a BMW, I was totally put off by the huge range of options. I can see why they do it, and appreciate the arguments about getting the perfect car for you, but that only applies new. Buying used, but knowing what I wanted in terms of options, it seemed like it was going to be utterly insurmountable to actually find the right car - none ever seemed to have the right combination.
That pushed me in large part to my final choice, which has no options as everything available is on it from scratch, so you reduce the hunt to age/miles/colour/price/history.
classic- elegance-avant garde- whats what? -
In a nutshell, Elegance is comfort orientated and Avantgarde is more sporty, but it's more of a "theme" than anything else. In fact on the latest C Class they've dropped the Avantgarde name in the UK and it's called Sport.