First, a thanks to Ocelot for linking my blog article on the more common juice delivery devices.
Cartotanks have been around for a couple of years now without many variations other than parts or materials used. The tube material can be either clear plastic (polycarbonate), frosted plastic (polypropylene), pyrex or quartz glass, or metal. The end cap material can be acrylic, delrin, or metal. Some tanks have a juice fill hole either in the top cap or in the tube. All cartotanks use a cartomizer with holes which allows juice from the tank to enter the cartomizer while vaping.
The AMP tank is a new tank system which uses a dripping atomizer in place of the cartomizer in a tank. It is in its first version, and it is often wise to wait for expected improvements to made with future versions before purchasing items unless you are a gadget lover that likes to buy the first new thing out on the market. I've heard both good and bad things about the AMP tank. There are some threads on the AMP tank here on the forum in the tank sub-forum if you seek more info.
Theoretically vaping on an atomizer is the purest form of juice delivery and flavor production. No wicking materials to affect the flow of juice to the heating coil or alter the flavor of the juice. The main con of using an atomizer is the ritual required to drip a few drops of juice, vape it a few times, and add a few more drops, vape some more. It's a ritual, and the constant activity of dripping frequently can be a pain in certain situations, such as driving and vaping.