Yes. The eGo-t "introduced" the
tank model on the Joyetech line. It has leaking issues, and you can't replace the atomizer core itself. You'd have to buy the atomizer base, atomizer core, and atomizer housing unit, I believe. Higher TCO, total cost of ownership.
The eGo-C means "changeable" in terms of the atomizer core. The atomzier base, core and housing unit comes apart, exposing the atomizer core, which can be replaced as a consumable item when it eventually dies. Lower TCO.
The eGo-C still leaks around the
tank/mouthpiece. I upgraded to three Kanger T3 bottom coil clearomizers to put on top of my eGo-C 1000mah twist batteries, and it's a great startup piece. Get the eGo-C starter kit if that's what you think is for you, and then get some Kanger T3 bottom
coils, and some replacement coils @ 2.5ohms.