Lyric is available as Dual Position Air/ Solo Air / Coil. What do those terms mean generally?

My speculations are leading me nowhere. If Dual Air means no hydraulic cylinder, how can the fork have Damping: Rebound? Solo air is pretty clear, but what about coil - is it a coil in one boot and hydraulic unit in the other, or two coils?

On a related note, do there exist shocks with both air and coil spring in the same time? If so, what is the point? How can one discern them?