A cartomizer is an atomizer with filler material inside. You don't drip into a cartomizer, you need to let the filler material soak up the e-liquid until it's completely saturated before you vape.
An atomizer has a metal outer layer with the heating coil inside, no filler. They can either have a bridge or be debridged (bridgeless), and you directly drip your juice onto the heating coil and vape. You don't fill the atomizer, you use just a few drops at a time or you wind up flooding it.
You drip into an RDA (rebuildable dripping atomizer), but an RBA has a tank for the juice and is not specifically made for dripping.
I agree with you in that, if you're a new vaper, I'd go with a good tank system first before getting into direct dripping.