A atomizer is the heating part of the vapor device which is old typle of e-cigarette.You need to use it with a tank or catridge, and the tank in most case is where the liquid holds and it is the mouthpiece.You need to clean the tank from time to time to keep it clean.Here is a piece of the atomizer.
A cartomizer is the atomizer and cartridge in one unit. Your 'T" is an atomizer and tank.Like the classical 510 cartomizer, The tank it uses mostly are plastic and white, some are transpanrent but some not. Here is a 510-T cartomizer
Clearomizer just like it says, it is clear some are in colored plastic tube now.It conbines the atomizer and the tank and the mouthpiece together.There are many kinds of clearomizer on the market, from CE serial, Stardust, and now there are mega tank,like kanger pro-tank vivi nova.There is also a new style clearomizer which is called bottom coil cartomizer.Like the EVOD clearomizer. Here is a photo of vivi style clearomizer