Every stair case I’ve ever looked down you see the landing for the next floor.
I’ve never seen one that has a hollow core the stairs wrap around.
Here is one example of many. The staircase is the part with the stairs. The stairwell is the space the staircase ascends and descends through. In some stairwells, the switchback of the stairs is only inches wide. In other stairwells there's a central space that may be many, many, many stories high. If you fall into it the right way, you can go all the way to the bottom.
