In strut suspension a telescopic type shock absorber is contained inside the strut with the coil spring mounted over the strut inside the suspension tower. The control arm mount is fixed (or 'held in place') in the vehicle configuration, by bushes.
In short/long arm suspension the lower control arm pivots on bushes that twist on the lower control arm pin, which is bolted to the cross-member of the vehicle. The lower control arm is longer than the upper control arm.
The torsion bar supports the vehicle load and twists around its center to provide the springing action. The spring rate depends upon the length of the bar. The shorter and thicker the bar, the stiffer its spring rate.
