What is the difference between hex socket bolts and external hex socket bolts?

Hexagonal bolts are very common in our daily life, and they are often used to connect various objects. There are two types of hexagonal bolts: hex socket bolts and external hex socket bolts. So, what is the difference between them?

First of all, the appearance of hex socket bolts and external hex socket bolts is different. The head of the external hex socket bolt is a regular hexagon on the outside, while the head of the internal hexagonal bolt is round on the outside, and there is a concave hexagon in the middle of the head. So the difference in their appearance is the different positions of the hexagons. Then, their fastening tools are also different. Due to the round head of the internal hexagonal bolt, an "L"-shaped wrench is required. In contrast, the head of the external hex socket bolt is hexagonal, so a hexagonal wrench is required, and the common ones are plum wrenches. From the perspective of cost, the use cost of external hex socket bolt is lower. From the perspective of use, external hex socket bolts are suitable for connecting large equipment, and internal hex socket boltss are suitable for connecting small equipment.