Activity Diagram

Is a UML flow based process-view diagram.

The structure of an activity diagram is the same as a state machine diagram, making it easy to confuse the two.

Table 1: Listing of the core see page 22, [differences] between state and activity diagrams.

Activity Diagram	State Machine Diagram
All the activity happens in the nodes.	All the activity happens on the transitions.
The flows just represent transfer of control.	The states are quiscent (if used properly).