As Oedipus begins his search for the person responsible for the misfortune of Thebes, there is tremendous dramatic irony as each of the characters that come forth to present evidence are reluctant to do so, as they either know or suspect what Oedipus has yet to discover - that he is searching for himself. This demonstrates the change in Oedipus between the Prologue and Scene 1.
In the Prologue Oedipus is presented as a model king:
Tell me, and never doubt that I will help you
In every way I can; I should be heartless
Were I not moved to find you suppliant here.
Clearly Oedipus shows that he is concerned, sympathetic, and eager to help his subjects. He takes his position seriously and recognises that as King of Thebes he must take responsibility for sorting out the problems that his kingdom and his people are facing. Note how this opinion is reinforced by Oedipus's reference to his subjects as "Poor children".
However, in Scene 1, we see that Oedipus, driven by his desire to find out the identity of the killer of Laius, insists that Teiresias reveal what he knows. The reluctance of Teiresias to share his knowledge drives Oedipus to insult him:
What a wicked old man you are! You'd try a stone's
Patience! Out with it! Have you no feeling at all?
He goes on to call Teiresias "arrogant", "shameless", "worthless" and finally:
You sightless, witless, senseless, mad old man!
Teiresias, who ironically only wants to not hurt Oedipus by the truth, suffers the wrath of Oedipus for wanting to help him. Oedipus is presented in a negative way as his thirst for the truth is driving him to insult a respected prophet.
Therefore the significant difference concerns Oedipus's presentation as the ideal king, who then moves to insult and curse those who are reluctant to give him the information he is looking for.