Nabi is the prophet who is not only for a certain section of humanity. Although he may live and move only in a limited region of the world, what he brings has its bearing upon the whole humanity. It may not be fulfilled in his lifetime, but a day of fulfillment comes, even if it is some centuries later that all he brought reaches the whole humanity. Rasul is a term which denotes an advanced degree, where the prophet has not only brought a message to the world, but fulfilled his task during his lifetime, through all the tests and trials that a prophet is meant to meet in life.