Yarn VS Thread?

thread

Fine cord of a fibrous material, such as cotton or flax, made of two or more filaments twisted together and used in needlework and the weaving of cloth.

Thread is a tightly twisted strand of two or more plys of yarn that are circular when cut in cross section. It is used for hand sewing and in home sewing machines. Ninety-five percent of all sewing thread that is manufactured is used in commercial and industrial sewing. Sewing thread is distinguished from yarn by the fact that thread is used to sew together garments or other products, but yarn is the collection of fibers used to weave or knit into a textile fabric. The terms are confusing and are often used interchangeably; thread can be made of yarn, but yarn is not made of threads.

yarn

A continuous strand of twisted threads of natural or synthetic material, such as wool or nylon, used in weaving or knitting.

Continuous strand of fibres grouped or twisted together and used to construct textile fabrics. Yarns are made from both natural and synthetic fibres, in filament or staple form. Filament is very long fibre, including the natural fibre silk and the synthetic fibres. Most fibres that occur in nature are fairly short, or staple, and synthetic fibres may be cut into short, uniform lengths to form staple. Spinning is the process of drawing out and twisting a mass of cleaned, prepared fibres. Filament yarns generally require less twist than do staple yarns. More twist produces stronger yarn; low twist produces softer, shinier yarn. Two or more single strands may be twisted together to form ply yarn. Knitting yarns have less twist than weaving yarns. "Thread", used for sewing, is a tightly twisted ply yarn.