CJ1M is newer than CQM1.
CQM1 was introduced in the early 1990s.
It was based on C200H platform (C Series PLCs).
The CJ1 family was released in ~ 2002, and has gone through several versions (original, V2, V3, and now V4).
The CJ1 family (CJ1M, CJ1G, CJ1H) are MUCH more capable and versatile processors.
They are faster, have more memory, on board comment storage, many more communications options, more IO options, same instruction set as CS1, CP1H, and other current Omron processors.
The CJ1G and CJ1H can have expansion racks, although the CJ1M cannot.
Are you looking at upgrading, or a new project?