There are several types of conning towers.
In the stock conning tower you typically first receive there is no step down between those two areas you describe. (See 2 images below)
(model)
(actual boat)
there appears to be no step as you are describing, though im interested in seeing if this is what you are talking about or not.
what is pictured above is the conning tower deck where it joins the
first Flak Turm.
there is however a very pronounced step between the first flak turm and the second flak turm in boats that are so equipped... see pic below
many people have seen images of the conning tower and have noticed how the watch crew is a good 10 inches taller than the men standing around the flak gun...
this is simply because of the wooden fold up steps that the watch crew has the option of folding down and stepping onto... these steps are about 10-12 inches above the hard deck.