afaik, all relates to the top shock mount position, on a single wishbone set up that is. Ie, caster relates to the angle of the shock and king pin, with top shock mount set rearward of the steering knuckle and quickens the stearing the steeper it is, much like a bike. Think chopper, very slow heavy steering, or sports bike with forks far more vertical, gives far quicker steering. The steeper the angle the more the wheel leans over when turned.
But more than that, what happens when you set the top shock mount more inboard of the king pin/steering knuckle position? I think, but not certain, that the wheel will lean still further, over and above the caster angle...? A way of getting the wheel to lean into the turn without too quick steering?
The advantage being, in any event, that the wheel is less likely to role off the rim if it leans into the turn and gives more grip......afaik anyway. :-)