“A repeatable way of dealing with a particular Category of Change. A Change Model defines specific pre-defined steps that will be followed for a Change of this Category. Change Models may be very simple, with no requirement for approval (e.g. Password Reset) or may be very complex with many steps that require approval (e.g. major software Release).” ¹

The change models are described in the Change Management Framework. These may also be referred to as "change process models".

For example, a change model for a minor impact change request might mean that only the Change Manager is involved in approving the change request, whereas the change model for a major impact change request might involve the entire Change Advisory Board (CAB).

¹ ITIL® V3 Glossary