What is the primary distinction between "turning" and "milling" operations?

The distinction between turning and milling operations lies in how the workpieces and tools interact during the machining process. Turning specifically refers to the operation where the workpiece is held and rotated against a stationary cutting tool. This allows for the creation of cylindrical shapes, as the cutting edge of the tool travels along the surface of the rotating workpiece, removing material to define the desired contours.

In contrast, milling involves a rotating cutting tool that moves across the stationary workpiece. The tool, which has multiple cutting edges, can reach various angles to create flat, curved, or complex geometries on the workpiece's surface.

While all options relate to some aspect of these operations, the primary distinction is correctly captured by the option stating that turning involves rotating the workpiece against a cutting tool, while milling utilizes a rotating tool on a stationary workpiece. This clear differentiation outlines the inverse relationship between the movements of the workpiece and the cutter in each operation type, which is essential to understanding the fundamentals of machining processes.