MadMac

Can anyone help me understand the difference between "traction control" and Vehicle Skid Control (VSC) which is offered on the 2002 Camry? I think Lexus offers both and they seem to be different (TRAC and VSC).
If they are different, is a traction control system available on the Camry either stock or aftermarket, and can it be installed on a Camry already equipped with VSC, or would they be redundant?