What are the differences between tensioned corrugated beam and untensioned corrugated beam?

Tensioned corrugated beam is mainly used in high speed road while untensioned corrugated beam is mainly used in low speed road.

Tensioned corrugated beam is designed mainly for use on central reservation. When a vehicle crashes into tensioned corrugated beam, the beam remains in tension while the post gives way to allow for deformation.
Tensioned corrugated beam absorbs impact energy by deflecting as a whole and helps the vehicle decelerate, and at the same time guide it back towards the carriageway in a gradual and controlled manner. Tensioned corrugated beam is normally not used on curves with radius less than 120m.

Untensioned corrugated beam is commonly used for road bends where radius of curvature is small as the use of untensioned beam does not require tensioning device. It is designed to deform in beams and to re-direct impacting vehicles on a course as close as possible parallel to the barrier.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.