Hi Nazz,
I have a particular liking for Kurlansky's 'Non-Violence, the history of a dangerous idea' his explanation is one that I like,
On p.6 he states "Nonviolence is not the same thing as pacifism, for which there are many words. Pacifism is treated almost as a psychological condition. It is a state of mind. Pacifism is passive but non-violence is active. Pacifism is harmless and therefore easier to accept than nonviolence which is dangerous. When Jesus Christ said that a victim should turn the other cheek he was preaching pacifism. But when he said that an enemy should be won over with the power of love, he was preaching nonviolence. Nonviolence, exactly like violence, is a means of persuasion, a technique for political activism, a recipe for prevailing."