A Reverend is just an ordinary priest.
A Right Reverend is a bishop.
A Very Reverend is the Dean of a cathedral or seminary.
The Reverend Canon is a Canon (associate priest) of a Cathedral.
After we crossed the Tiber, I called the archbishop "Your Grace" without thinking . . . which is correct for both Anglican and Catholic archbishops in Britain . . . but not in the U.S. (he is apparently "Your Excellency" here . . . cardinals are "Your Eminence" everywhere. One of my dad's friends who is a judge addresses other judges as "Your Eminence" . . . just a personal quirk.)
Thanks. I take the low road and call all of them "Sir."