There are three kinds of actions:
Reusable action - An action that can be called multiple times by the test with which it is stored (the local test), as well as by other tests.
Non-reusable action -An action that can be called only in the test with which it is stored, and can be called only once.
External action - A reusable action stored with another test. External actions are read-only in the calling test, but you can choose to use a local, editable copy of the Data Table information for the external action.
refer QTP Help.
Reusable action - An action that can be called multiple times by the test with which it is stored (the local test), as well as by other tests.
Non-reusable action -An action that can be called only in the test with which it is stored, and can be called only once.
External action - A reusable action stored with another test. External actions are read-only in the calling test, but you can choose to use a local, editable copy of the Data Table information for the external action.
refer QTP Help.