I'm confused about the three different types of processes in the CMMI - Performed, Managed, and Defined? Aren't they all just defined?
Well, to be more precise there are FIVE process types in the model - the three you mentioned plus "Quantitative" and "Optimizing." Those two represent ML4 and ML5 - but I digress.
The three process “types” you’ve asked about each have different attributes.
A “performed” process may be improvised, has no policy, training, QA, et al, but includes the basic practices needed to execute the process on a project.
A “Managed” process has all of the attributes of the “performed” process but is executed in accordance with a policy, is planned, has resources assigned, people are trained, etc (all of the GPs for GG2).
A "Defined" process is a process composed using the organizations set of standard processes following a set of guidelines and is improved over time. (GG3). The process that results from any of these may or may not include everything needed to complete a project from start to finish (for example, it could address only Requirements Management and not Project Planning). It does, however, typically include much of what is needed in practice and ALWAYS “lives” within a project.
Just to add to the confusion, a “Tailored” process IS a Defined process. A Defined Process IS a “Tailored” process. If a Managed” process is tailored, is derived from a set of standard processes, and the “user” contributes to the PAL and measurement repository, it is a “defined process.”
Finaly, an “institutionalized” process can be either a “managed” process (GG2) OR a “defined process.” (GG3). The Generic goals indicate the "degree" of institutionalization.
Whew! And we're just getting started!