A critical distinction between maturity levels 2 and 3 is the scope of standards, process descriptions, and procedures.
At maturity level 2, the standards, process descriptions, and procedures can be quite different in each specific instance of the process (e.g., on a particular project).
At maturity level 3, the standards, process descriptions, and procedures for a project are tailored from the organization’s set of standard processes to suit a particular project or organizational unit and therefore are more consistent except for the differences allowed by the tailoring guidelines.