The main difference between the Sophists and the other philosophers is that the Sophists were essentially rhetoric teachers, while the other philosophers were more interested in seeking the truth.
The Sophists were rhetoric teachers, and their focus was on the art of persuasion by using language. They were wise intellectual people, and they tried to use and teach their abilities of persuasion by using language to the wider masses.
The philosophers, on the other hand, were focused on knowing the truth, they wanted to be wiser by knowing the truth instead of dogmatically stand by the false beliefs. So they were trying to teach the wider masses the ways as to how to come to the truth and wisdom.
