In dialogue, finding common ground is the goal. In debate, winning is the goal. Dialogue enlarges and possibly changes a participant's point of view. Debate affirms a participant's point of view.
Dialogue reveals assumptions for reevaluation.
Debate defends assumptions as truth . Dialogue causes introspection on one's own position. Debate causes critique of the other position. Dialogue opens the possibility of reaching a better solution than any of the original solutions. Debate defends one's own positions as the best solution and excludes other solutions.