I'll attempt a break down and see if I succeed...
A Device is an object that does something so every component of a vaporizer can be called a Device.
Mechanical, or Mech Mod, is a battery holder and switch that has no electronics. (That means no protection circuitry either.)
A Rebuildable is just that, it is a device that can be rebuilt. I use a rebuildable dripping atomizer so when the coil stops working right I can open it up and either fix it or rebuild it with some wire and wick. I don't have to buy another unit.
A Mod usually refers to a battery and switch that is either not mass produced or that has a replaceable battery. The ECF term APV is suppose to refer to a mass produced Mod, but it is not in universal use. The first Mods, and many still today, are built from re-purposed parts with whatever tools the builder has available. You could MODify a flashlight to be a battery holder and switch, as an example, and thus the term Mod.
Variable Voltage is a device that allows you to vary the voltage delivered.
Variable Wattage is a device that allows you to vary the Wattage delivered.
A Hybrid, typically, means a device that is a battery holder, switch, and rebuildable atomizer with tank all in one unit. These are usually Mechanical Mods, but do not have to be.
So, all of them are devices, but other than that they are not really the same thing. Well, we could say that since Wattage is a product of Voltage and Current then Variable Voltage is the same as Variable Wattage, but a Variable Voltage device is set to a voltage while a Variable Wattage device is set to a wattage, much the same but different units of measure and the term comes from the unit of measure that is set.
You'll have to see if the vapeing gods are forgiving as I haven't encountered any. The folks on ECF are pretty friendly though.
