In a dab pen the heater and atomizer are the same thing. It is a heating element that when power is added, heats up like your stove top. As the heater heats up it starts to boil and then vaporizes the oils.
One thing to note is when the oils run out in a vape pen the heater/atomizer can overheat and burn out. The oils actually help to prolong the life of the element as they keep it cool.
The wax maxer actually has 3 types of heaters
Ceramic (this is one of the best heaters as the heater is built into the ceramic eliminating oxidation. This extends the life of the heater as there is not oxidation that will kill the heater)
Quartz (This is a heater that has the element built into the quartz glass.)
Coil (this is a wire wrapped around a quartz rod. Some will call this a quartz heater, this is not true. This is a coil heater if you see the metal coil)