High-speed steel (HSS) and tool steel are both types of steel that are known for their hardness and durability. However, it is important to note that high-speed steel is actually a type of tool steel with specific properties that make it suitable for high-speed applications such as cutting tools.    In terms of hardness, both high-speed steel and other tool steels can have similar hardness levels. The hardness of a steel is typically measured on the Rockwell hardness scale, and different grades of both high-speed steel and tool steel can have varying hardness values.   It is important to consider that the hardness of a steel is influenced by several factors such as the specific alloy composition, heat treatment, and the intended application. So, while high-speed steel is generally known for its high hardness, there are many different types of tool steels available, and some tool steels may have comparable or even higher hardness levels than high-speed steel.   Ultimately, the choice between high-speed steel and other tool steels depends on the specific requirements of the application, such as the cutting speed, heat resistance, and wear resistance needed. It is recommended to consult with a materials expert or supplier to determine the best steel for your specific needs.