Square bar refers to a square-shaped material produced by hot-rolling square billets, or by cold-drawing round steel.

Square tubing refers to a tubular shape with a square cross-section. It can be made from a variety of materials, though most square tubing is made from steel pipes. The process involves uncoiling, flattening, rolling, and welding to form a round tube, which is then rolled into a square tube and cut to the required length. It is typically packaged in bundles of 50 pieces.

In the spot market, square tubes are predominantly available in large sizes, ranging from 10 × 10 × 0.8–1.5 to 500 × 500 × 10–25. Square tubes are classified by application into structural square tubes, decorative square tubes, construction square tubes, and mechanical square tubes, among others.

A square tube is a type of square-shaped tubular material, specifically a steel tube with equal side lengths. It is manufactured by rolling steel strip through a series of processing steps.

Solid, classified as bar stock. It is generally produced through hot rolling and can be further processed into round steel, anchor bolts, and other products, such as railroad tracks.

Hollow, classified as tubing. It typically features rounded corners and is lighter in weight than square steel. Smaller diameters are generally cold-rolled, while larger diameters are typically welded together and used for structural applications.