@ Elliott - as Kevin said, they are all recessed. On the second picture, the part below is still "flat". You can see the difference in the third picture, which shows the same part, already in "3D".
@ Kevin - thanks
According to the instruction booklet, the subject of the first pictures is the switchgear building. It includes a row of eleven modules. In each of them, I added 3 card bits and a paper roll, in order to ease assembly.
The other building has almost no detail. It is the “circulating water structures” building, whatever that means.