What is this decoration called that's found around ceilings and doors, as shown in the images below?
In general, those are moldings, also spelled moulding.
The one around the top of a wall is called a crown molding.
The particular shape used in that example makes it an (somewhat elaborated) ogee molding.
A molding slightly lower on the wall is called a picture molding or picture rail because it can be used to hang pictures from.
A molding about 3 feet above the ground is called a chair rail because it is (possibly) used to prevent the backs of chairs damaging the wall.
I don't know if there's a special name for the molding used on the doors. It could possibly be called a panel molding because it is used to visually separate the panels of those doors from the rails and stiles (the members of the frame that holds the panel).
Both of these shapes can be generically described as millwork.
There are specific terms related to the position of the millwork in the overall fabrication, and terms related to the design of the millwork itself, but millwork covers all of these.