Whats the difference and on my 93 xj which type do i have???

best way is to look at your front driveshaft and rear driveshaft. your stock rear will just be a single U-Joint. the front driveshaft where it comes out of the tcase is a CV(constant velocity) joint, its like a double u-joint lookin thing

What's the difference....

A U/J can only transmit torque through relatively small angles. A CV joint can accomodate much greater angles without breakage.

Very approximately at 15 degress a U/J service life is cut by 75% whereas a CV joint will tolerate 20 degrees for a long time.

Chris L.