differences between annular and iris diaphragm in a microscope?with simplified words ....Thanx

An annular diaphragm and an iris diaphragm both adjust the
amount of light that passes through a specimen in a microscope, but they do this in
different ways. In an iris diaphragm, a lever or wheel is used to adjust the positions
of a set of moving plates (sometimes referred to as "leaves"). As the leaves shift
position, a hole in the center of the leaves is made smaller or larger. The size of this
hole controls how much light passes through to the
specimen.

An annular diaphragm consists of a plate with a
series of holes of different sizes in it. The microscope user turns the plate to line
one of the holes up with the light path. The size of the hole chosen determines the
amount of light that passes through.