The difference between "elements" and "controls" is not that important in practice, but it is useful to understand the distinction.
Elements derive from
(directly or indirectly), but not from
Control. They have some look and provide some functionality that is customizable mostly by changing properties. For example,
Ellipse is an element. There's no way to change the fundamental appearance of an
Ellipse (and it would be illogical to be able to turn an
Ellipse into, for example, a rectangle). It can still be customized in some ways using properties such as
Controls, on the other hand, derive (directly or indirectly) from the
Control adds ...