In Director 8.0 and earlier, a cast member could be any entity that plays a role in the movie: a digitized sound, a graphic, a piece of text, a button, an icon, or even a script or behavior.

These kinds of 2D cast members play an important role in Director 8.5 as well, but the new 3D cast members are different. A 3D cast member contains an entire 3D world, including the models that populate that world and the actions that take place in it.

In Director 8.0 and earlier, a sprite was an instance of a cast member—an example of the cast member at a particular section of the score. If you changed a sprite, you didn't change the cast member, but if you changed the cast member, you changed all its sprites.

These kinds of sprites still exist in Director 8.5 as instances of 2D cast members. A 3D sprite, however, is different, because each sprite of a 3D cast member can contain different views into that cast member by means of cameras. Each camera provides a view of the 3D world's contents: one camera may look toward the front of a model, and another may look at the side of the model. Because each sprite of a 3D cast member can be set to use a different camera for its view, the various sprites of a single 3D cast member can have different appearances.