Question about a product

Length: 400 m
Thicker: 40 count (cotton)

Filament yarn refers to yarn made by combining long fibers, like silk yarn. Filament yarn is characterized by its sheen and strength even when thin.
Thin, strong, and lustrous filament yarn is suitable for textiles such as silk and wool.

Spun yarn refers to yarn made by combining short staple fibers. Spun yarn blends easily into textiles and is easy to sew with.
Spun yarn with a fuzzy surface is suitable for cotton and textiles with a cotton-like texture.