Think of the Nano as a "micro" tank. It has a tank to hold the liquid. Inside that is an internal poly filler like a carto that feeds a wick and a coil. Overall, this makes it exactly like a larger tank system shrunken down to a nominal 1ml size. Given how small everything has to be to fit inside each other, keep in mind the actual wick/coil assembly is inside a fiber tube inside the chrome air tube with the poly fill which is inside the chrome air tube, the coil and wick are quite small.
The CE3 only has the wick and coil inside the air tube so the wick is directly fed by the liquid in the "tank" with no poly fill. Liquid consumption does seem higher, but keep in mind that the CE3 seems to produce more vapor than carto style devices and that much vapor does take more liquid to produce it.
The CE3 only has the wick and coil inside the air tube so the wick is directly fed by the liquid in the "tank" with no poly fill. Liquid consumption does seem higher, but keep in mind that the CE3 seems to produce more vapor than carto style devices and that much vapor does take more liquid to produce it.