The best way I heard it described is something like this. When you use the gas pedal to determine your speed that's VV. When you use speed control button that's VW. So imagine your on a flat road...i.e. your resistance isn't changing...it doesn't matter if you use the gas pedal and hold your foot at a constant angle or if you are using speed control...your speed is going to stay the same.
Now lets say you encounter a hill and 20 mph winds coming head on (i.e. the resistance of your atty got higher). With the gas pedal (VV) you need to step on the pedal a little more to overcome the wind and the hill just to maintain the same speed. When using speed control (VW) the car's computer takes care of that for you and your speed remains constant regardless of the resistance.
Same analogy when going down hill just in reverse.
Assuming all things being equal juice, tank, battery, etc when switching from a lower resistance atty to a higher resistance atty and vice verse you will get the exact same vape when using VW. The mods computer chip kicks in determines what the appropriate voltage should be to equal your current wattage setting (i.e speed of car)...Just like how a car's computer determines how much gas to send to the fuel injector when using speed control.
Regardless of using VV or VW
wattage is the end result that determines the hotness and throat hit of the vape. Wattage in this case equates to the heat/energy given off by the attomizer to turn the liquid into a vapor. You can look at ohms law and all of that but when increasing the voltage your actually increasing the wattage and when decreasing the voltage you are decreasing the wattage. There is a formula that uses voltage and resistance to calculate the wattage. When using VW it uses that formula behind the scene and calculates what voltage you need for your given wattage setting based on the resistance of the attomizer that is currently in use.
In all honesty if all of your atties are the same resistance (you are always driving on a flat road) it makes no difference what you use as the resistance becomes constant. The advantage of using VW is that when you change resistances you shouldn't have to change any settings as the vape will be the same. Again from my previous post I still tweak for different juices, times of day, and mood but I have to do less fiddling.
The only other advantage I can see to VW is that when I change my battery it keeps my wattage setting...but when I'm using VV and I switch batteries it always resets the voltage to the lowest setting.
Hopefully that description helps cement things in your mind a bit easier than going over ohms law and physic and math equations
One other advantage of VW...the resistance of your atty changes over time and usage. When using VW your device picks up on this and will adjust the voltage output accordingly to maintain your current wattage setting.