streetlight98: There are some mistakes in your description about the different types of MH lamps:
1. Probe start metal halide: A metal halide lamp that have three electrodes in the arctube (Two main electrodes and one for starting), and a starting resistor. With the US ballasts, it can be operated without an ignitor, like a MV lamp. This is indeed correct that these are simply improved color MV lamps.
2. Pulse start metal halide: A metal halide lamp without a starting resistor and with only two electrodes in the arctube. Requires an ignitor like the high pressure sodium lamp (HPS).
Because its arctube design without the extra starting electrode is better (The arctube can be also shaped better), they have usually longer half life (Hours to 50% light output) and better color shift (Light output degrades to 50% and color significantly shifts only at or after the end of the lamp rated life, and not after only 100 hours of operation like the probe start lamps). Pulse start metal halide lamps, have also faster run-up and shorter hot restrike if operated in the correct equipment.
3. Ceramic metal halide (CMH): A pulse start metal halide lamp that have a ceramic arctube instead of a quartz arctube. Because the ceramic material can operate at higher temperature, the efficiency and color rendering can be increased. For the american market, the increased color rendering related only to the improved halide chimestry over the american quartz metal halide lamps (QMH) (Dy,Ho,Tm,Tl,Na in almost all CMH vs Na,Sc in all american QMH).