What is a RBA atomizer?
RDA = Rebuildable Dripping Atomizer - You directly drip e-liquid on the wick/coil, it does not hold a lot of liquid at a time. Have to re-fill' liquid more often, but easier to make and change out coils, wicks, and customize the Ohm output.
RBA = ReBuildable Atomizer - These usually have a tank that holds liquid, so you don't have to refill your liquid as quickly as an RDA. You still build your own coils/wicks, but isn't as easy to replace/change/modify as an RDA.