What is the difference between an archbishop and a 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. There is a regulation that a cardinal who is not already a bishop must be ordained to the episcopate, but this rule can be dispensed. So, with permission, it is possible for a layman or a priest to be a cardinal.