difference between state chart,state machine diagrams and state transition diagrams

Question

what are the differences between state chart diagrams, state machine diagrams and state transition diagrams? while at several places i got to learn that state chart diagrams and state machine diagrams mean the same thing but at some places it is shown as different.i could only make out that state chart diagrams represent states the system is in at a moment of time while state machine diagrams show the objects and transitions between them throughout their lifetime.

Answer 1

UML state machine diagram also known as UML statechart diagram. It shows state transitions in the system.

So in UML context, practically they all refer the same thing.

But "state diagrams" exist before UML and has many different kinds and drawing styles.

Answer 2

Tim Weilkiens mentioned in his work "Systems Engineering with SysML/UML":

The UML state machines are based on the work of David Harel who, among other things, combined the theory of the general Mealy and Moore machines to create a model that lets you describe complex system behavior.

So there were Statecharts (diagrams) and then came State Machines