There are a lot of people when you hear them talking about RenderMan and how great the images are from it, etc. They are most likely really talking about Pixar's PhotoRealistic RenderMan® (PRMan).
So the reasons for this confusion between RenderMan the spec and PRMan the renderer are:
1. Pixar publishes and owns the RenderMan Interface SpecificationRenderMan Interface Bytestream (RIB), very simply, is the file format used to pass scene information (model data, lights, camera, shaders, attributes, and options) to a RenderMan renderer to control image that it will render. At the 2003 SIGGRAPH, Dana Batali (Director or RenderMan Product Development at Pixar) shared an interesting historical slide showing some of the major milestones on evolution of RIB. (which has been around publicly for 15+ years)
2. RenderMan is a registered trademark of Pixar.
3. Pixar had the first implementation (PRMan).
4. PRMan has been used in a lot of movies.
5. Not only was PRMan the first implementation of the RenderMan
Specification, it was for many years the only implementation.
Es interesante todo esto que lei y aprendi de la pagina oficial www.renderman.org