There is no difference.
Limited slip is the generic term for any traction device that works via friction.
Positraction is a marketing term GM used from the 50's to the 70's. Similar to cola versus Coca-Cola . Call them whatever name you're most comfortable with, they'll still work the same. All of the small but very important parts are included in our Installation Kits and Overhaul Kits . Well here is the truth some don't want you to know.