The Difference Is...
The difference is that one is bad for you and the other is worse. It doesn't matter which. When I low-carb, I drink them, too, can't help it but there is a strong belief by the ultra-serious low-carb community (usenet, etc) and by Dr Atkins, that aspartame somehow interferes with ketosis which is the whole point of low-carbing for most people trying to cut bf% down.
Low-carb'ing, in general, helps if a person was over-carb'ing before, but if one isn't going to get into ketosis for 6 days or so (ckd style recomp on day 7) then I don't get the point of it? Carbs are energy. Either NORMAL carb, or get into KETOSIS with VERY LOW carb so fat is used as energy.
I think it's common knowledge now that long-term ketosis wreaks havoc on the system, but along the lines of BodyOpus and Anabolic Diet, it's fine.
Oh yeah, the point is....stay away from em both if you can. Check out SoBe Lean and check into some Splenda (which is probably just as bad for you but Atkins recommends it so it MUST be good, right?! lol)
B