what is the difference between outer hexagons and inner hexagons

Do you know why they are both hexagons, and what is the difference between outer hexagons and inner hexagons?

Here, I will talk about them in detail from the appearance, fastening tools, cost, etc.

Exterior

Everyone should be familiar with external hexagonal bolts/screws, which are bolts/screws with hexagonal heads and no recesses on the heads;

The outer edge of the head of a hexagon socket bolt is round, and the middle is a concave hexagon. The more common ones are cylindrical head hexagons, pan head hexagons, countersunk head hexagons, flat head hexagons, headless screws, Stop screws, machine screws, etc. are called headless hexagon sockets.

Fastening tools

The most common tightening tools for external hexagonal bolts/screws are wrenches with equilateral hexagonal heads, such as adjustable wrenches, torx wrenches, open-end wrenches, etc.;

The shape of the wrench for hexagon socket bolts/screws is "L" shape. One side is long and the other is short. The short side is used to tighten the screws. Holding the long side can save effort and tighten the screws better.

cost

The cost of external hex bolts/screws is lower, almost half of that of internal hex bolts/screws.