These orb chandeliers are based around a sphere shape. Sometimes there is more than one sphere. But generally the light fixtures/bulbs are inside of a sphere. The orb is formed by the framework of the orb chandelier and produces an overall round profile.
A modern globe chandelier
These globe chandeliers are a modern and popular twist on a typical chandelier shape, since usually chandeliers have arms which reach out and form various shapes. Here the globe chandelier breaks with tradition and models itself on a simple sphere shape.
Some orb chandeliers are wood orb chandeliers where some of the spherical parts are wooden. With a sphere chandelier you're adding a modern statement to a traditional idea.