Yarn and fiber

Staple fibers are of finite length. The lengths of individual fibers could be measured in inches. Filament fibers, such as silk, are very very long, measuring in hundreds of yards or even miles.

Staple fibers are held together by twist to form yarn that is longer than the length of the individual fibers. Filament fibers are twisted together to create greater strength or thickness, but not greater length.
Bulk Continuous Filament (BCF) fibers tend to be less fuzzy and smoother than staple fibers (depending on preparation and blending).