What is the primary difference between a bolt and a screw?

• A. A bolt is threaded into a preformed internal thread in the component.
• B. A bolt passes through holes and is usually fastened with a nut.
• C. A bolt requires a nut and threaded hole.
• D. A bolt and screw are identical in application.

Answer: (B)

The main idea is how the fastener engages the parts. A bolt is designed to go through holes in the components and be secured with a nut on the opposite side, which clamps the parts together. This is why the typical description is that a bolt passes through holes and is usually fastened with a nut. Screws, by contrast, are meant to thread into the material itself (either into a pre-tapped hole or by creating their own threads in the material), so they don’t rely on a nut to clamp. The option that matches the common practice—passing through holes and being fastened with a nut—best captures the primary difference. The other ideas describe scenarios that aren’t the standard distinction: bolts threaded into an internal hole, or bolts requiring a threaded hole on the workpiece, or the two fasteners being identical in use.