On a lot of websites, and in a lot of product descriptions you will see the words Atomizer, Cartomizer, and Clearomizer. Basically all of these words describe the same part: the piece that screws on top of your battery that you put the material you want to vaporizer into. To make things simpler for newcomers we will generally describe the part as an 'Atomizer' regardless of its technical classification. In most cases it is easy to distinguish the difference by looking.

They have different names because they represent different technologies. and have different advantages and disadvantages.

Atomizer: Generally an atomizer has a heating coil at the bottom. Sometime the coil is covered by a metal mesh or wick. Material can be pressed or dripped onto coil. Generally dry herbs vaporizers will use this technology.
PROS: Great for dripping eLiquids. Simple design is easy to us. Often Low cost.
CONS: Need to refill a lot. Hard to tell how much material is left.


Cartomizer: Catomizers normally have a cylinder going down the middle with heating coil(s) in it. Normally this technology is used for eLiquids.
PROS: Hold more material. Fairly easy to rebuild and fix.
CONS: Often retains previous flavor

Clearomizer: Clearomizers are generally plastic or pyrex and have a clear (sometimes translucent colors) tank. Some have top coils, some have bottom coils. For eLiquids they will often have long or short wicks protruding from the coil. 
PROS: Can see how much material you have left easily. Come in large capacities. Often rebuildable.
CONS: Usually more expensive. Some leak (not ours). 

What matters most tends not to be the specific technology but instead the quality of the implementation of that technology.  All types have great and horrible models. Vape Pens Sales strives to carry the highest level of quality products.