Levels are used in CMMI solutions to describe evolutionary paths recommended for organizations that wish to improve their processes used to acquire, develop, and deliver products and services. Levels can also be the outcome of the rating activity in SCAMPI appraisals.
CMMI for Acquisition, CMMI for Development, and CMMI for Services all support both capability levels and maturity levels. The People CMM supports maturity levels only.
Capability levels enable your organization to focus its process improvement efforts process area by process area from capability level 0 to capability level 3. Once you select a process area, you decide how much you want to improve the processes associated with that process area (i.e. select the appropriate capability level). The achievement of capability levels is illustrated in a capability profile.
Maturity levels provide a staging of processes for improvement across your organization from maturity level 1 to maturity level 5. This improvement involves achieving the goals
of the process areas at each maturity level. Process areas can be grouped by maturity level, indicating which process areas to implement to achieve each maturity level. Maturity levels are illustrated by a single number (e.g. maturity level 3).
To reach a particular level, an organization satisfies all of the goals of the process area or set of process areas that are targeted for improvement, regardless of whether it is a capability or a maturity level. Both are valid ways to improve your processes to achieve business objectives; and both provide the same essential content and use the same model components.
Your process improvement goals should always be based on your business objective. Experience has shown that organizations benefit from achieving a level only when the focus of improvement is on shared higher-level objectives, not a focus on achieving the level itself. When the focus is on achieving business objectives, the levels result naturally.Source: partners.clearmodel.com