The X2 clearomizer is topcoil clear plastic that holds 1.6ml of liquid and can be used on all of the volt batteries. Because of the topcoil design, you get very warm vapor and great taste. It is filled from the top. You can also just rinse them out under hot running water between fillings. I usually rinse them after the third refill or before changing flavors.
The T3 is a bottom coil clearomizer that holds about 3ml of liquid. Because the coil is at the bottom, the vapor is cooler and it's filled from the bottom. At this time, the T3 can only be used on the X2 and the Volt spinners. SI is currently working on making them compatible with the 65 and 78mm batteries. Another great feature of the T3 is the bottom coils are replaceable so you don't have to replace the entire unit. Cleaning them is also easy by rinsing in hot water. Another thing to note is the draw on the T3 can be too airy for some.
Some people prefer one over the other so my suggestion is to try each to decide which you prefer. SI will be carrying a smaller T3 that basically will have the same features as the larger version but not hold as much liquid. Trying out new things can be great fun.
Hope this helps you to enjoy your vaping experience!
