Could you post some pictures of the wheels? I'm assuming the wheels are mecanum given the angle. The difference between mecanum and omni wheels is that while omni's have smaller wheels "perpendicular" to the larger wheel, Mecanum wheels have smaller wheels positioned at 45 degree angles all around the larger wheel. Mecanum wheels allow a robot with the right programming to strafe side to side or diagonally in different directions. I believe Omni wheels can move side to side but not diagonally. And, while mecanum wheels can move side to side based on the direction they are driving to eachother, omni's need another power source to move them sideways.
Here is a link to a thread that talks about the subject in more detail. I've done a poor job explaining.
http://www.chiefdelphi.com/forums/sh...ad.php?t=57282