The one that is written down — procedures, permits, the management system as it appears in the document register.
And the one that actually happens at three in the morning on the third night of a turnaround.
The distance between them is where incidents live.
Most organisations respond by restating the first system more loudly. More training, more signage, more reminders that the procedure exists. This treats the gap as an information problem. It rarely is. People know the procedure. They are not following it because something makes following it harder than not following it.
That something is friction — and friction can be moved. Out of the correct action, so the right way is the path of least resistance. Into the shortcut, so the wrong move costs something.