No parametric, sweepable mids on older model.
Better S/N ratio on forthcoming one (doesn't say what, though).
36% lower power consumption: maybe it will run a bit cooler than the last one??? I did see reports that the old one runs very hot, but I have no experience of it...
...and less significantly, perhaps:
Wider knob spacing. Well I have got big fingers, but then they've been expensively trained to have superior motor-skills over years of guitar practice, so I'd like to think I'd have managed with the old ones!
Removeable end bits - totally useless! I bet no one ever takes them off.
I'm not sure this is an exhaustive list, but that's what I can gather from the Alesis pages.