The key difference lies in the wire form and aggressiveness:

• Twisted Wire Wheel: Made from strands of wire twisted together into bundles. The ends are blunt, offering better flexibility, milder cutting action, and larger contact area. It is less likely to dig into the workpiece, making it ideal for cleaning, deburring, rust removal, and finishing.

• Knotted (Straight) Wire Wheel: The wires are straight and cut, resulting in sharper ends. It is more aggressive and sharper, suitable for removing heavy scale, weld spatter, and stubborn deposits, but may leave marks on softer materials.