When you look at a hard top window treatments you might initially have trouble determining if they are cornices or pelmets. Cornices and Pelmets are often used interchangeably. They are both hard window treatments that decorate the top edge of the window; however, they are technically slightly different. A cornice means a ledge and refers to a horizontal decorative molding that crowns a building, piece of furniture or window . The function of a building cornice is to throw rainwater off the building, and in that regard it is similar to the eves or roof edge. The difference between the eves and cornice is that the cornice has decorative molding attached.  The combination of the decorative molding and the eves gives the cornice is characteristic projecting crown, plus one of myriad types of decoration.

The decorations added to the cornice can appear in many different forms. While true cornices (as opposed to pelmets) all have a projecting crown at the top, they differ in the shape of the sub layers of decoration. There may be a middle layer of carved wood, for example, sitting between smaller jutting cornice crown like projections, each subsequent projection smaller than the one above it. The possibilities are endless when we consider ;that the size of each projection, its shape and its height; and the number of projections and their size, height, and curvature can vary extensively.

The pelmet is a palm leaf like decoration that generally conceals curtain fixtures. In fact, etymologically, the word derive from the  old English word palmette or palm leaf like decorative covering. The pelmet in comparison to the cornice is missing a crown and various layers of decorative molding found in cornices. The pelmet, in fact, frequently consists of a flat layer of decorative fabric covering a wood frame that sits at the top of the window treatment (drape, shade or blind), and covers it.  Pelmets are often cloth covered, whereas cornices are more likely to be made of wood, plaster, or faux wood.  Another essential difference between cornices and pelmets is that the cornices are related to the crown molding of a room as it interacts with the window, whereas the pelmet relates to covering the top of the window or other structure and not forming part of the room molding in any way.