Coach bolts, also known as carriage bolts, are extremely heavy duty, used to fasten metal to wood or other heavy woods. They are ideal for structures which require a sturdy joint.
Coach screws are heavy duty screws designed for metal to timber connections, or to join heavy timbers. Also known as lag bolts or lag screws, they have a square or hexagonal head engineered to be used with a wrench, spanner, or pliers.