In what respects does a UML state diagram differ from a state transition diagram?

Answer: The difference between the UML state diagram and state transition diagram are as follow:-

State-transition diagrams display the states of the object where the change takes place whereas the UML (Unified modeling language) state diagrams are representation of parts of system at certain time instance. State-transition diagram requires the condition to be accomplished before the transition happens whereas the dynamic behavior of the states are expressed by transitions in UML state diagrams.