Regular characters
Lazarus and Lazarus Risen show up as separate entries, as do Judas and Black Judas. Each card lists starting hearts, consumables and items, so you can compare Cain's two red hearts and Lucky Foot against Magdalene's four and Yum Heart.
Tainted characters
Repentance gave 17 characters a tainted twin with a new title. Tainted Isaac is The Broken, Tainted Magdalene The Dauntless, Tainted Cain The Hoarder. Several start with a pocket active instead of a passive item, and Tainted Cain's is the Bag of Crafting.