Denim is made from tightly woven twill constructed from cotton, although cotton blends using spandex or polyester are also common. During construction of denim, the weft slips under two or more warp threads to create a rugged twill. Typically, the lengthwise thread is dyed with the standard indigo color. The horizontal thread is generally white. Because the twill is woven so tightly, the indigo color appears most prominently, leading to the classic heathered look of denim fabric. While corduroy is also made using one warp and two fillings, the threads are almost always the same color, leading to a more uniform look.

While it’s true that both fabrics have ribbing, denim is distinguished by diagonal ribbing that can be identified on the reverse of the fabric. Corduroy, on the other hand, is distinguished with ribbing that runs vertically, specifically called “wales.” In addition, denim ribbing is typically fine, whereas corduroy ribbing can range from 1.5-to-21 wales per inch but usually has 10-to-12 wales per inch.

Corduroy has been historically known as the fabric of royals since it emerged some 2,000 years ago when Italian merchants introduced the fabric to European nobles. The modern fabric known as corduroy was first mass produced in Manchester, England, during the Industrial Revolution in the 18th century and became the working man’s choice because of its ruggedness, warmth and ability to withstand tough conditions. It was later dubbed the “poor man’s velvet.” Its popularity waned, although the fabric made a comeback in the last decades of the 20th century. Denim, on the other hand, has been known as a working-class product without royal affiliation at all. The fabric has been historically used to make men’s work clothes. By the mid-20th century it had evolved into a fashion staple used by all social classes.

Similar to denim, corduroy is made in a variety of prints, colors and styles. Denim, though, also comes in a variety of washes to the finished fabric, ranging from acid wash to pinto, stone and ice washing. Corduroy has few washes to differentiate the fabric, relying mainly on prints and colors to distinguish its varieties.