In design term, whats difference between Overlay and Overlap

Question

In design term, whats difference between Overlay and Overlap

Answer 1

To overlay something is to put another surface on top of an existing one. For instance, you might want to overlay a semi-sheer fabric of a contrasting color onto another, denser fabric to achieve a soft, more feminine look.

To overlap is to smoothly make a transition from one material to the next. For instance, in drapery, the part of the drape that covers the transverse rod, is the overlap.

Generally, think this way...overlay...lay another surface to cover...overlap...on top of but not covering.