Qustion on Castle/Nue motor sizes and capablities??

So I am ready to drop the hammer on one of these combos...well I have already ordered one with the LHS but I was wondering something. (should be here in 3days)

I thought I read that the 2200 was "larger" motor than the 2650 and could handle more volts (22.2) then the 2650 which is only recommended for 4s lipo. I thought I read this or heard this from castle, but I might have heard wrong.

The reason I ask is I ordered the 2200 combo.
My thinking is lower kv=cooler running and more gearing/lipo options. There is going to be a time when I want to really push the limits on this motor in the speed dept. Not all the time just to get my speed fix.

But I noticed today that on castle website that the motors are listed weighting exacly the same at 121grams. I thought the 2200 was a bigger can and more suited for truggies with extra weight....I have the 8ight buggy and am wondering why the 2650 cannot handle 6s. Then I could run 5s lipo for around the track or even 4s.

This is my 1st 1/8 conversion so I just want to make the right decision. Any help or information for this noob would be greatly appreciated.
Paul