President Joseph F. Smith explained:
The Priesthood in general is the authority given to man to act for God. Every man that has been ordained to any degree of the Priesthood, has this authority dedicated to him.Challenge: Priesthood holders, use your priesthood power and keys as authorized. Women, support the men in doing so.
But it is necessary that every act performed under this authority, shall be done at the proper time and place, in the proper way, and after the proper order. The power of directing these labors constitute the keys of the Priesthood. In their fullness, these keys are held by only one person at a time, the prophet and president of The Church. He may delegate any portion of this power to another, in which case that person holds the keys of that particular labor. Thus, the president of a temple, the president of a stake, the bishop of a ward, the president of a mission, the president of a quorum, each holds the keys of the labors performed in that particular body or locality. His Priesthood is not increased by this special appointment, for a seventy who presides over a mission has no more Priesthood than a seventy who labors under his direction; and the president of an elders’ quorum, for example, has no more Priesthood than any member of that quorum. But he holds the power of directing the official labors performed in the mission or the quorum, or in other words, the keys of that division of that work. So it is throughout all the ramifications of the Priesthood—a distinction must be carefully made between the general authority, and the directing of the labors performed by that authority. (“Distinction between Keys of the Priesthood and Priesthood,” Improvement Era, Jan. 1901, p. 230.)