What is the difference between a screw and a bolt?

Answer 1

a cap screw has a top bigger than the threaded portion [a cap]. the cap screw does not sit flush with the material being screwed into. a machine screw has a tapered top that fits into a countersunk hole and when screwed in is flush with the surface being screwed into;

Answer 2

Screws have threads and bolts sometimes do and sometimes don't have threads.

Screws join things together, wood or metal or plastic. Bolts have a nut on the other end and may use washers or spacers. Bolts need a hole drilled for them, a screw may not if it is self tapping.

Bolts hold the material and usually compress it.

Screws are held by the material and are usually compressed by it.
Bolts have / use nuts or some sort of a compatible threaded interface.
Screws are compression fit into or thru and held tight by a material like wood, metal, plastic or bone (perish the thought).
The term screw and bolt are often used interchangeably.

It is the same hardware - just a different application.

Technically, a screw is assembled into a tapped hole and torqued at the head. A bolt is inserted through a clearance hole and fastened by a nut. It is tightened by torque on the nut.
what is the difference Between Screw & Bolts.
Bolts are kept from unthreading themselves by the use of a nut. Screws rely totally on the friction between the threads and the material into which they are emplaced.

Answer 3

Bolts are kept from unthreading themselves by the use of a nut. Screws rely totally on the friction between the threads and the material into which they are emplaced.