What if any is the relationship between "Turn display off " and "Sleep"

The guides are quite clear that "sleep" is only available via a menu or "schedule" in "Energy saver" but in that area there is an option to turn off display which seems to result in the screen first fading and later going blank - but then there is the line below about stopping auto sleep; but as stated they have indicated that there is no auto - sleep. Does anyone (including Apple) know whether the reference to "auto" actually means "if scheduled" or does the device go to sleep after some undefined criterion after the display has been turned off.