The load-carrying ability of a coil spring depends on the wire diameter, the overall spring diameter, its shape, and the spacing of the coils. Coil springs can look alike but give very different load ratings, which are often color coded for identification.
A leaf spring locates the axle housing longitudinally and laterally. It sustains torque reaction on acceleration, and braking torque on deceleration. Driving thrust transfers through the front half of the spring to the fixed shackle point.
A torsion bar is fixed to the chassis or sub-frame at one end, and the suspension control arm at the other. Deflection of the suspension causes the bar to twist around its center, to provide the springing action.
Increasing the load on a suspension causes the rubber cone to act like a spring being deformed. When the load is removed, the rubber's elastic properties tend to return it to its original state.
