No I think that's not what he wants to know

When you have your Level it is saved as kind of rowmaterial in an wmp file. This only contains information about position and properties of all levelobjects that you placed. In the build process, this will be compiled into a wmb file, which contains also information about visibility and shadows so a precalculation of light settings and a mechanism to order the levelsurfaces belonging what is visible in the scene and what's not. In A7 this process does even more, but that's out of my range to explain in Detail.
Whenever you want to use static lightning, levelgeometrie and a predefined levelspace you need to build a level to make it working.
EDIT: Xarthor was faster, that's exactly what I wanted to say, of course
