The 8084 is a substantially different e-cig from the 4081. The 4081 is a standard sized mini - about 103mm long, something like 8.5 or 9mm diameter, with a 180mah battery. The 8084 is sized the same as an ordinary cig, with a 100mah battery.
It's not a hopeless design, unlike many of the tiny e-cigs - you can get some vapor and throat hit out if it, and the cart design is somewhat easier to switch, and refill, with an inner cartridge that fits loosely in the mouthpiece, and a treaded cap so that you only change the inner cart, not the mouthpiece. It's a 4 hole atomizer though, and that is IMHO far too much air for the quantity of vapor produced. For my purposes, even when I was using the 4081, I wasn't getting enough out of it to keep around. However my friend and his wife, who I handed it on to, are quite happy with it as an alternative to analogs.