e-cigarettes are battery-operated pen vapes that heat up a propylene-glycol or vegetable-glycerin based e-liquids (with or without nicotine and flavourings) with a wire and let you inhale the vapor. They are simple healthier alternatives to cigarettes.
You can only fill them with e-liquids.
Classic vapes are designed with a bowl for ground herbs (tobacco, cannabis or anything else).
That bowl and/or the air that is going through the bowl is heated up vaporizing all the good out of the herbs.
They are more complicated than e-cigs, because it's not as easy for a device to vaporize herbs than a concentrate.
If you want to vape cannabis concentate, then you need something else.
Either a vaporizer that has a bowl modification allowing it to also vape concentrates.
Or a dab pen, which is like e-cig but for cannabis waxes instead of e-liquids.
Or you can get an e-nail for classic dabbing, but that is not as portable like dabbing pens.