What does this tell readers and viewers about Hamlet’s character?

Discussion

In Act 3, Scene 3, Hamlet has an opportunity to kill Claudius, but he does not act. One scene later, however, Hamlet does not hesitate at all when he kills Polonius in Gertrude’s chamber.

Why is Hamlet able to act in Scene 4 but not in Scene 3?

What does this tell readers and viewers about Hamlet’s character?