Most vape mods available for purchase today are regulated mods. This means that a chipset sits between the battery and the coil, allowing you to select the wattage, as well as a bunch of other parameters.
On the other end of the spectrum are mechanical devices, which have no chipset in them and have to be built around the specifications of your battery. Mechanical devices are essentially just a tube that holds your battery and will always fire at full power. Mechanical mods are not recommended unless you really know what you are doing.
Sat in the middle of these two types are unregulated mods.