RBA = ReBuildable Atomizer. - This is any type of atomizer that is designed to be rebuilt with a new coil or wick. It is also used to describe the the removable section that is exchanged with a pre-made coil. RTA = Rebuildable Tank Atomizer - This is a complete atomizer that coil section is designed to be rebuilt. RDA = Rebuildable Dripping Atomizer - This is a complete atomizer that has no tank and requires you to drip e-liquid on the coil and wick to vape it. The part that provides the power to run it can be called many things: APV = Advanced Personal Vaporizer, mod, battery, device, and many other things. On the SubTank Mini. All version 1 were stainless steel only and had only 1 large Airflow slot, and the RBA section had no holes in it. Version 2 were stainless, black, white, and possibly other colors. The tank was the only real difference. The tank was the SubTank mini V2 and the Mod (the part that supplies the power) was a SubBox Mini.