For 100 watt lamps I've seen "M90" "M90/E" and "M90/O". If a ballast says "M90" and "ceramic metal halide" with 100 watts will it run any 100 watt PSMH lamp?

M90 is the ANSI code for 100Watt Pulse Start Metal Halide
E = Must be used in an enclosed fixture
O = Open rated Can be used in either an open or enclosed fixture
I am not sure about the ceramic metal halide lamps though sorry

The ceramic have slightly different characteristics (because they are of quite a different chemistry), however I don't think there is any ballast that may run only one of them.

The enclosed/open rating is for lamps and fixtures, the ballast does not differ at all.
In similar manner some suffixes mean different sockets (E26 vs Rx7s vs Gxxx), so again al;though the lamps difer in the complete ANSI designation, the ballast is the same.