After some research, it appears this is how it works with monsignors:
"A Catholic priest is given the title of Monsignor by the Pope in recognition of outstanding service to the Catholic Church. A monsignor is still a priest but also has this great honor to his name.
The process begins once a diocese bishop nominates a priest for this high honor. The bishop submits the priest's name, biography and works to the Holy See. At that point, the Pope reviews the information and determines whether or not to make the priest a monsignor. The Vatican will issue a diploma designating the new title and rank.
There are three grades of monsignor. The Protonotary Apostolic is given to a priest who serves seven positions in the Roman Curia. A Protonotary Apostolic wears a black cassock with red buttons and a fuchsia sash and cape. A grade 2 monsignor is Prelate of Honor to His Holiness. It can be given to priests outside the papal court. The Prelate of Honor to His Holiness wears a bishop's choir cassock and a fuchsia sash. The Chaplain to His Holiness is grade 3 and is given to a priest inside or outside the Roman Curia. They wear a black cassock with a fuchsia sash."