Whats the difference between an ATB (automatic torque biasing) differential using helitical gears and a standard LSD

i know the LSD uses clutch plates and helps put the power down to the wheel with most resistance. but the ATB differential in its discription says it does the same. but doesnt wear out as it hasnt got clutch plates like the lsd's (not that i know as i have only ever had standard differentials)

so. whats the difference??
including what can be used with more power?
which would be better to drive/race with
same but drifting
etc etc etc
Pro's and cons please as the ATB is cheaper but i want to know... why havent i heard of these before?