The Ceremonies explained

Knight Companion: The 1st Degree of the Order that of Knight Companion, leads from the Pagan Dispensation to the Christian, using the Legend of Constantine the Great as a symbol of that conversion. The candidate comes as a "Knight of Rome" desiring to embrace Christianity, and he must, in accordance with the General Statutes of the Order, be a Royal Arch Mason. The key message of the Ceremony and the Order is the legend of Constantine's conversion to the Christian Faith.

Priest Mason: The 2nd Degree is that of Venerable Eusebius and is one of the symbolic Priesthoods. A Knight who has attained this status is eligible for the office of Eminent Viceroy in a Conclave provided he is a member of the Appendant Orders of the Holy Sepulchre and of St. John the Evangelist and that he is regularly elected to that office.

Prince Mason: The 3rd Degree is confined to the Most Puissant Sovereign, who represents Constantine, Sovereign-Prince of the East and West. A Sovereign shall have served for one year in the office of Viceroy in a regular Conclave. This Degree completes the Rite of the Red Cross of Constantine.

Knight of the Holy Sepulchre: The Appendant Orders of the Holy Sepulchre and of St. John the Evangelist were attached to the Order of the Red Cross of Constantine at an early date and a separate certificate is issued to members of this Order. There is no connection, historically or ritually, between the Masonic Degree of Knight of the Holy Sepulchre and the medieval Military Order of the same name, which is said to have been founded in the eleventh century.