Schmeichel's sweeping was less systematic – making him less of an actual sweeper-keeper. Not that Neuer is the first of that sort either.
As for the rest – the intimidating, swashbuckling style, the long throws, the more-than-active presence in the box...aye, no way Neuer has anything on Schmechel in those regards. Plus, Schmeichel was better on the line than Neuer too.
I reckon
@Gio summed it up very well above. Neuer is brilliant at what he does and a perfect fit for a certain kind of team – namely a monstrous one, bound to be dominating nine games out of ten, playing with a high line, etc. The keeper – truly – becomes another defender, not just sporadically, but pretty much permanently. We could easily see that Neuer becomes the model for a whole generation of keepers – which will be interesting, if it actually happens: Because he would start to look like a liability very soon if he were to feature for a shabby-ish team, playing the same game.