Arrogance is believing you are better than others. Ambition is the desire to make a difference. Arrogance is the belief that you're indispensable. Ambition is doing whatever it takes to accomplish what you know you deserve. Arrogance is thinking that the world owes you something, and doing what you can to take it.
Ambition is disciplined and assertive.
Arrogance is pushy. Ambition is responsible and respectful. Arrogance is destructive and disdainful. Arrogance will drive you into the ground. Ambition will drive you to the top.