The benefit of using VW over VV is you can set it and forget it.
In variable voltage if you have a 2.2 ohm carto, you have to set the voltage to where you like it. Then, say you put a 2.8 ohm Vivi Nova on, you have to adjust the voltage to get that same vape experience.
Variable Wattage lets you find the wattage setting you like, then when you put a different device on it, it will automatically adjust the voltage to provide the same vape experience. So whether you have a 2.2ohm carto, a 2.8 vivi nova, a 3.0 carto, or a 1.5 dual coil, the vape experience will be relatively the same.
In short:
Variable voltage: adjust voltage everytime you chance your atty
Variable wattage: set it and forget it
