A locker works by locking the two side gears of the differential to the carrier. In a manual selectable locker the two wheels are in 100% lock until the locker is disengaged. In an automatic locker the two wheels are always locked together until one needs to spin faster than the other, as is the case when cornering. Automatic lockers work in the reverse of limited slips in that they're normally locked and only unlock during turns, rather than being normally unlocked and only resisting wheel speed difference during slip. A locker is better than a limited slip because it will give the driver 100% lock and won't give out when a large amount of slip is encountered.