Bolts. While screws are often colloquially referred to as bolts, they are not the same. While screws thread into parts, bolts are used to join two non-threaded parts, typically using a nut. A screw extractor would not be used to remove a boltbecause it is not threaded into the parts.

Screws are generally turned into an object, like a piece of wood, so the head needs to be bigger than the surface. … The shafts of bolts are not tapered, whereas manyscrews are tapered. The main difference between a bolt and a screw is that a typical screw can work on its own and a bolt requires a nut to secure it.