Difference between State Transition Diagram and Data Flow Diagram?

How can we define the difference between State Transition Diagram and Data Flow Diagram?

State Transition diagrams are used to model the behavior of one object over several use cases in the system. A state describes the condition of an object at a given point in its lifetime. A state diagram describes all possible states of an object, and the paths to get from one state to another when an external event is received. But, a Data Flow Diagram (DFD) is a graphical representation of flow of information or data throughout the system.