What are the differences between sandpaper and steel wool in terms of their effectiveness for smoothing surfaces?

Sandpaper and steel wool are both abrasive materials used for smoothing surfaces, but they have different properties that affect their effectiveness. Sandpaper is made of paper or cloth with abrasive particles bonded to the surface, and it is good for smoothing wood and other materials. Steel wool, on the other hand, is made of fine steel fibers and is more abrasive than sandpaper, making it better for removing rust and paint from metal surfaces. Overall, sandpaper is better for general surface smoothing, while steel wool is more effective for tougher jobs on metal surfaces.