Socket Head Allen Bolt:

In 1919, Dyke defined them as screws that are threaded all the way to the head. A socket head allen bolt, also known as, socket screw, or Allen bolt. It is a type of cap screw with a cylindrical head and hexagonal drive hole. Most Socket Head Cap Screws are designed with a small head, followed by a smooth rod. And then threaded to the end of the screw.

General:

A standard inch series of this bolts is 20% stronger than a Grade 8  and 50% stronger than a Grade 5. It have a small cylindrical head with tall vertical sides. It socket drive is a six-sided recess for use with an allen wrench (hex key). Whereas a wide range of socket screws, useful in a variety of applications requiring a strong bolt or screw where access is limited. Socket screws are also known as Allen head screws or bolts, and are fastened using a hexagonal or shaped wrench, requiring a key to tighten and remove. Standard sizes available from stock. Socket head cap screws are typically used in machine parts, die fixturing, and clamping. Socket head cap screws are ideal for applications in which there is not enough space to maneuver wrenches or sockets.