They all ultimately accomplish the same thing... some with greater convenience and length of time between refilling, some better for new rebuilders, some offer better flavour and some offer the option of using extreme low resistance.

Rebuildable RDA - RBA - RDTA 

Dripping RDA

* RBA - Rebuildable atomizer. Encompasses all variations of rebuildable device. The 'Genesis' type atomizer (more below) may be the genesis for the term.

* RDA - Rebuildable dripping atomizer. Typified by a short, 510 base, sufficient to hold a coil or coils, with a small juice well to drip juice into via the drip tip. Often the most flavorful, and most often used for sub-ohm vaping. At one time, the Nimbus was one of the most popular RDAs... now, with the relatively recent advent of 'original design today - clone tomorrow' China forgeries, any new genuine RDA that comes out is copied within a few weeks.

Deep well

The Origen, Magma, Veritas, Tugboat, Plume Veil, 454, Vulcan, CLT - and whatever comes out tomorrow are popular - with 'deep well' RDAs, both horizontal and vertical coil designs jumping to the top of the most desirable list. By extension, a genesis atomizer is a variation of an RDA, typically (although not always) on top of a juice container which feeds the RDA via a combination of gravity and/or capillary action. The nature of the design is often exemplified by a wick made from stainless steel mesh or rope. The RSST might be the most prevalent of Genesis type attys, as it's one both old hands and n00bs might have on their desk.

* RTA - Rebuildable tank atomizer. A pressure differential liquid tank that surrounds and feeds the atomization chamber. The SvoeMesto Kayfun3.1/KFL+ and Kebo Russian/R91% have held the top spots in both genuine and clone RTA popularity, with the Taifun GT, sQuape and Fogger V4 and Flash-E Vapor in hot pursuit.

New RTAs

New RTAs come out, from all around the world, every few weeks. The Gus Estia and Inverno Erlkönigin are two that although currently only available in genuine form, will become very popular once cloned. There are also gravity/capillary fed, non-pressure differential tanks that use a batting material to hold juice and feed the wick. The GP Heron and Spheroid are of this type. I've left out lots of atomizers... the list would go on forever. Pairings of RBA and PV are interesting. Low resistance RDAs and 'gennys' are usually found on unregulated mech mods, while RTAs can be found on everything from a tube mech mod or Provari... to the common MVP2 APV.