On 21/10/2020 21:21, Bob Eager wrote:
Tell that to a coach screw!

No, a bolt has an unthreaded section. A screw is threaded all the way
along.

There are machine screws, and wood screws, and grub screws, and...

.... and I have a large collection of wood _screws_ many of which are
unthreaded near the head It's only recently they've started being
threaded all the way up.

What's the difference between a pan head and a wafer head?

Andy