Polypropylene fibers can be broadly classified into two categories: polypropylene filament and polypropylene monofilament. As the names suggest, the most obvious difference lies in their yarn structure: polypropylene filament typically refers to a composite yarn composed of multiple monofilaments, such as 2-ply or 3-ply yarns; while polypropylene monofilament is a single, continuous fiber, resembling fishing line.

In specifications, polypropylene filament is often indicated by "D/F," such as 24F or 36F, meaning it consists of 24 or 36 monofilaments. Polypropylene monofilament, on the other hand, has a single fineness and is not ply-stranded.