The main difference between a steel bar and a steel rod lies in their shape and typical applications. Steel bars usually have a flat, square, or rectangular cross-section, while steel rods are typically round and solid. Bars are commonly used in construction and manufacturing for structural support, machinery parts, and fabrication due to their broad surface area and strength. Rods, on the other hand, are often used in applications requiring flexibility, precision, or machining, such as fasteners, shafts, and pins. Both steel bars and rods can be made from various steel grades, including carbon steel, alloy steel, and stainless steel, but their choice depends on the specific mechanical properties and shapes needed for the project. Overall, bars are favored for heavy-duty structural uses, while rods suit more detailed or round-shape requirements.