OK.. I'll break down as much as I can.. hopefully someone else will do the rest..
CE2 is the new fillerless carto. It went through many 'revisions'. Hence the R3 (revision 3) R4 (revision 4). The latest is ce2 R4. Which breaks down to Carto Edition 2 Revision 4. It has a ceramic cup, silicone seals, and a wick inside. It comes in two sizes: reg and XL
Now they are making them clear. Same carto, clear outside.
New names: Clearomiser, Fluxomizer, clear ce2, etc.
ALSO, new on the market is the Tank.
The Tank is completely different beast. It is a new type of atomizer to which you attach a fillerless tank full of liquid. It's like using the old 2 piece 510 unit, except the 'cart' has no filler.. it's enclosed and it clicks onto a point of the atomiser which draws out the liquid. It is not supposed to leak. This atty will ONLY work with the special tank carts.
NOW.. to make things more confusing.. There are the MAP Tank Mods.
This is essentially a combination of the above. Someone has taken the filler (the inner workings) of the CE2 cartos out of their casing and put them into a BIGGER casing.. thus it will hold more liquid.