Ottoman is a fabric with a pronounced ribbed or corded effect, often made of silk or a mixture of cotton and other silk like yarns. It is mostly used for formal dress and in particular, legal dress (such as QC

Queen's Counsel

Queen's Counsel , known as King's Counsel during the reign of a male sovereign, are lawyers appointed by letters patent to be one of Her [or His] Majesty's Counsel learned in the law...

 gowns) and academic dress

Academic dress

Academic dress or academical dress is a traditional form of clothing for academic settings, primarily tertiary education, worn mainly by those that have been admitted to a university degree or hold a status that entitles them to assume them...

 (mostly for hoods

Hood (headgear)

A hood is a kind of headgear that covers most of the head and neck and sometimes the face. They may be worn for protection from the environment, for fashion, as a form of traditional dress or uniform, to prevent the wearer from seeing or to prevent the wearer from being identified.-History and...

).

Ottoman made of pure silk is very expensive so artificial silk is used instead to create a cheaper alternative.

Grosgrain

Grosgrain

Grosgrain , also gros-grain and, rarely, gros grain, is a type of fabric characterized by its ribbed appearance. In grosgrain, the weft is heavier than the warp, creating prominent transverse ribs. It is called a "corded" fabric since the weft resembles a fine cord. Grosgrain is a plain weave...

is similar to Ottoman but it is thinner and lighter than Ottoman and is used mostly for ribbons.