No difference with anger. V. Real issue at stake in this passage. It is an attack on legalism. Many Jews had the idea that if they had not been arrested for murder, they were alright with God. It is a human tendency - anything is permissible as long as you are not caught.
Murder begins in the soul.
All stand condemned. He was angry at injustice, we tend to get angry at personal affronts. Focus of Jesus here - personal relationships. Destroying this special relationship is the same as murder. The other part is to be a peacemaker.