Cardinals rank higher than bishops, so not all bishops are cardinals. But now all cardinals are bishops, although in the past there have been exceptions. George Pell is both a bishop and a cardinal, as well as the third-ranking official at the Vatican.

A bishop, therefore, who has been named a cardinal remains a bishop. This is why a diocesan bishop or archbishop can also be a cardinal. Historically, the bishops of particularly important dioceses throughout the world are normally named cardinals, as a sort of additional honor.

In the Catholic Church, the office of cardinal is further split up into the three ranks of bishop, priest and deacon. However, this rank has nothing to do with their ordination status, as most cardinals were previously ordained a bishop before receiving the special office of cardinal.

An archbishop is usually the bishop of a major metropolitan archdiocese and may also be a cardinal. A cardinal is a member of the college of cardinals, and, according to current requirements, is usually a bishop.