The holy priesthood is administered to the children of men according to different orders. As Joseph Smith taught, “All priesthood is Melchizedek, but there are different portions or degrees of it” (Teachings, p. 180).
The preparatory gospel (law of Moses) operates under that order we know as Aaronic. The fulness of the everlasting gospel operates under different orders. The Church operates under an ecclesiastical order of offices, quorums, and councils.
In our day one enters into the patriarchal order in holy temples through entering into the new and everlasting covenant of marriage (see D&C 131:1-4; Bruce R. McConkie, CR, October 1977, p. 50).
In addition, one enters into the holy order of God through proving worthy of all the blessings of the temple, through eventually receiving what the scriptures call the fulness of the priesthood.
President Ezra Taft Benson thus explained: “To enter into the order of the Son of God is the equivalent today of entering into the fulness of the Melchizedek Priesthood, which is only received in the house of the Lord” (Ensign, August 1985, p. 8).