External conflict is the conflict between characters at odd because of argument. And internal conflict is a struggle within a person's mind over a problem or question. This helps a person to know themselves and their quality. So, I think that internal conflict occur more often than external conflict.
They are close friends in the beginning of the play. http://webcache.googleusercontent.com/search?q=cache:yDbvfIrZYaAJ:www.studynotes.ie/wiki/macbeth-ban...