Sliver and roving are differentiated by the orientation of their fibers. Sliver contains fibers that are randomly arranged, while roving has fibers that are aligned parallel to each other to create a smoother preparation for spinning. Wool sliver is thinner than roving and has minimal, or no twist through its length, while wool roving has a small amount of twist and is generally going to be thicker and more uniform throughout.
Sliver is most often used in needle felting and spinning fine yarns, while roving is often used to create thicker yarns or felted objects. Helpful hint: sliver is pronounced "sly-ver."
