The two new classes, Wizard and Witch, were actually previewed some time back, and developer PearlAbyss and publisher Daum Games officially revealed the pair today. Armed with an array of devastating area-of-effect elemental skills, these two classes are beasts when fighting on an open field. Apparently, the Wizard will be able to teleport, while the Witch has aura abilities to aid party members.
I am not really sure what other differences there are between the two classes, but they are not really as easy to play as they sound. Notice in the trailer, they would have to frequently dodge and teleport away from enemy mobs, as the area-of-effect skills will aggro a horde of them. It becomes nasty if they are not killed in time. The Wizard and Witch were apparently added to the game today.