Flavor; Vapor and a certain amount of heat basically.
Many that use a non-variable voltage battery will use different ohm devices to get the flavor and vapor that they want from their
juice.
I prefer a variable volt device, that way I can adjust the voltage to optimize the flavor of my juice, which in turn, gives me a good overall vape.
Voltage and ohms basically create watts in the coil. Watts are a certain amount heat that the coil produces.
To much heat and some flavors in a juice can get burnt away or lost. Not enough heat and you don't seem to get enough flavor in the vape.....Does that make sense?