What would be the main ones?
Cardinals are higher ranked. They can choose and be the next pope.
Izzy is right. Cardinals are at the top tier of the Church hierarchy, just a level behind the Pope, who they elected and usually is one of them, and they depend directly from Rome, meaning who they are all members of the Church of Rome (as their titular church is there) and not of the local ones (unlike regular Bishops and Archbishops)