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. Debate creates a close-minded attitude, a determination to be right.
Dialogue calls for temporarily suspending one's beliefs.
Debate calls for investing wholeheartedly in one's beliefs . In dialogue, one searches for basic agreements. In debate, one searches for glaring differences. In dialogue, one searches for strengths in the other positions. In debate, one searches for flaws and weaknessess in the other position.