What is a compression spring?

Compression spring is to bear the pressure of the coil spring, it uses the material section is mostly round, but also useful rectangular and multi-stranded steel system, the spring is generally equal to the pitch, the shape of the compression springs are: cylindrical, Shaped, convex and concave and a small amount of non-circular, etc., compression spring between the circle and the circle has a certain gap, when subjected to external load when the spring shrinkage deformation, storage deformation energy.
What is a torsion spring? Torsion spring using the principle of leverage, through the material soft, toughness of the elastic material of the twist or rotation, so that it has great mechanical energy.