An application group is a way of grouping CICS® BAC objects -- files, TDQueues, transaction IDs, and programs. This is typically done to associate the objects with a particular application, such as Payroll. Grouping the objects under one application group allows you to address them as a single entity for purposes of batch request utility processing.
An application list is a way of associating CICS BAC application groups so that they also can be addressed as a single entity for purposes of batch request utility processing.