Wiki comes to the rescue again:
http://en.wikipedia.org/wiki/Limited_slip_differential
Basically with a 2-way diff the same amount amount of locking is applied regardless of whether the input torque is positive i.e. from engine, of negative i.e braking.
With a 1.5 way it is setup assymetrically to provide more locking with throttle than under braking.
With 1 way locking is only provided for throttle only (unless you install it the wrong way around!)
My understanding is that a 2way is prefered by drifters and a 1.5way is good for track (the slight locking during braking provides some stability).
http://en.wikipedia.org/wiki/Limited_slip_differential
Basically with a 2-way diff the same amount amount of locking is applied regardless of whether the input torque is positive i.e. from engine, of negative i.e braking.
With a 1.5 way it is setup assymetrically to provide more locking with throttle than under braking.
With 1 way locking is only provided for throttle only (unless you install it the wrong way around!)
My understanding is that a 2way is prefered by drifters and a 1.5way is good for track (the slight locking during braking provides some stability).