ATB is automatic torque biasing, and tries to send the power to the one with the most grip, basically exactly the opposite of an open diff.
Good in some situations, wank in others.

Normal viscous and plated LSDs dont try and be clever like that just lock both wheels together to some extent, making sure both wheels get power.

An LSD isnt an LSD though, not by a long shot, they will vary in how much they lock up in any given situation, how fast they lock up in any given situation, and what situatuations they lock up in (ie coasting, acceleration, and deceleration).
So can have ones that does nothing coasting, locks slightly on the brakes, and loads on acceleration, or any combo like that.
How it is setup affects how the car handles.