It is not much bigger but allows to use 3-ph current. That means 73% faster charging under 208/120 V (very common in a lot of charging stations). Of course, it supports 240 V split phase up to 125 A (almost double the usual 70 A of J1772). It also supports 140 A under DC. And with the Combo 2 plug it rises up to 200-250 A. Model S in Europe will have this socket in the car, modified to support SC. I think it is the ideal plug... And is not too late to change the code in USA and switch to the better plug. What do you think?