As mentioned Agile is a set of principles about how a methodology should be implemented to achieve the benefits of embracing change, close co-operation etc. These principles address some of the project management issues found in studies such as the Chaos Report by the Standish group.
Agile methodologies are created by the development and supporting teams to meet the principles. The methodology is made to fit the business and changed as appropriate.
SCRUM is a fixed set of processes to implement an incremental development methodology. Since the processes are fixed and not catered to the teams it cannot really be considered agile in the original sense of focus on individuals rather than processes.
