Joke Collection Website - Talk about mood - What's the difference between total area and surface area?

What's the difference between total area and surface area?

Where did you see the "full area"?

The surface area is usually the external surface area of the entity; The total area may be the sum of the inner and outer areas of the hollow body;

I'd better talk about specific image examples.

The cylindrical metal oil tank barrel of tanker only needs to be painted on the outer surface, and the painted area of the outer surface is the surface area;

The container is a cuboid, which may be painted inside and outside, so the total area is almost twice the surface area.