Dear Lee,

The main difference between the thermacool NXT and the CPT lies in the handpiece. The new white-small handpiece is a vibrating one, rather than the older blue handpiece. Both activate the same tips, but as I said the new one vibrates. This vibration intends to distract the patient from the the pain and discomfort sensation and make his sensory receptors on the skin receive vibration instead.
With the launch of the the new CPT system, they also launched a new line of tips with a different membrane (red and brown) on the tip cover. These tips provide what thermage calls comfort pulse technology. Hence the name CPT.
These tips are programed so that the cryogen coolant spray bursts are fired in short pulses during the 1.8 seconds of the radiofrequency wave pulse and therefore making the treatment 40% more comfortable.
I use thermage Thermacool NXT in my practice and to upgrade to the CPT handpiece, it costs around 15000$ US.

Regarding the results, I think its a bit to early to say because thermage results to begin with, are very different from one person's response to another, and they are highly variable.