Without getting confusing, the easiest way to explain the difference is with a metaphor relating to a car's transmission.
Variable voltage (VV) is like a manual transmission. You have more range and versatility, but if you go out of the "safe range" for your heating element, you risk burning out the coil.
Variable wattage (VW) is like an automatic transmission. Most good VW devices will give you a safe range (5-12w for example) where most heating elements can safely run.
This is not an exact science, and some VV or VW devices will be more accurate than others, but I find this is the best way to understand the difference without getting into math equations and whatnot.
Thoughts?
Variable voltage (VV) is like a manual transmission. You have more range and versatility, but if you go out of the "safe range" for your heating element, you risk burning out the coil.
Variable wattage (VW) is like an automatic transmission. Most good VW devices will give you a safe range (5-12w for example) where most heating elements can safely run.
This is not an exact science, and some VV or VW devices will be more accurate than others, but I find this is the best way to understand the difference without getting into math equations and whatnot.
Thoughts?