Rebuildable Drip Atomizers, aka RDAs, are atomizers that feature a mostly flat "build deck" where coils and wick is installed. Drippers offer a smaller profile than other atomizers, along with great flavor and cloud production as you have full control over the heating element installed.
Rebuildable Dripping Tank Atomizers, aka. RDTAs attempt to match the best flavor and cloud production that RDAs are known for, with the convenience and ease-of-use of a tank. They offer the best of both types of atomizers in the one unit! Similar to an RDA, they feature a deck to be built on, and juice drips downwards from the tank into the wick.