Solid Conductor
Solid-conductor cable is designed for backbone and horizontal cable runs. Use it for runs between two wiring closets or from the wiring closet to a wallplate. Solid cable shouldn’t be bent, flexed, or twisted repeatedly. Its attenuation is lower than that of stranded-conductor cable.
Stranded Conductor
Stranded cable is for use in shorter runs between network interface cards (NICs) and and wallplates or between concentrators and patch panels, hubs, and other rack mounted equipment. Stranded conductor cable is much more flexible than solid-core cable. However, attenuation is higher in stranded-conductor cable, so the total length of stranded cable in your system should be kept to a minimum to reduce signal degradation.