Calumny and detraction--what's the difference?

Today I was reading about the strange case of Fr. John Corapi, a Catholic priest I used to hear occasionally on the radio.  He was an excellent, challenging speaker, yet one day in 2011 he just disappeared.  Is his case calumny or detraction? Frankly, I don't know that I still understand the difference, and no one seems to know what has happened to Father Corapi.

"To put it in simple terms, calumny is the telling of a lie about someone, almost always with malicious intent—for instance, to damage his reputation. Detraction, on the other hand, is the telling of the truth about someone to a third party who has no right to that truth. Detraction is often done with malicious intent as well, but not always.

In more common terms, most of what we call gossip is detraction; most of what we call backbiting is calumny. The Catechism of the Catholic Church classifies detraction and calumny as "offenses against the truth" (and specifically, as the venerable Baltimore Catechism notes, both are violations of the Eighth Commandment). Both are sins, which can be either venial or mortal, depending on their intent and effects. Even when committed carelessly, without malicious intent, detraction and calumny can cause grave damage to the person being discussed, and the person guilty of detraction or calumny has an obligation to try to repair the damage done by his action."