Ceilings are classified according to their appearance or construction.
A cathedral ceiling is any tall ceiling area similar to those in a church.
This may be done for aesthetic purposes, such as achieving a desirable ceiling height; or practical purposes such as acoustic damping or providing a space for HVAC or piping.
A concave or barrel-shaped ceiling is curved or rounded upward, usually for visual or acoustical value, while a coffered ceiling is divided into a grid of recessed square or octagonal panels, also called a "lacunar ceiling".A cove ceiling uses a curved plaster transition between wall and ceiling; it is named for cove molding, a molding with a concave curve.1 A stretched ceiling (or stretch ceiling) uses a number of individual panels using material such as PVC fixed to a permieter railŹródło: https://en.wikipedia.org/wiki/Ceiling
A good example of the latter case is the stucco, plaster ornaments and so on the external walls and internal.
At their simplest, moldings are a means of applying light- and dark-shaded stripes to a structural objects without having to change the material or apply pigments.The contrast of dark and light areas gives definition to the object. Imagine the vertical surface of a wall lit by sunlight at an angle of about 45 degrees above the wall.
Adding a small overhanging horizontal molding to the surface of the wall will introduce a dark horizontal shadow below the molding, which in consequence is called a fillet molding.
Similarly, a cavetto above an ovolo forms an s with horizontal ends, called a cyma or cyma recta.Its shadow shows two dark bands with a light interior.Źródło: https://en.wikipedia.org/wiki/Molding_(decorative)#Theory.