(Quoted from here)For years, a vibrant network of third-party solutions (including V-Ray from Chaos Group, AccuRender from Robert McNeel & Associates, and many others) has been providing alternatives to and augmenting the existing rendering and visualization technology inside Autodesk applications such as AutoCAD, Inventor, and Revit. Even Autodesk’s two best-known animation and visualization products, 3ds Max and Maya, work with a variety of third-party rendering products.
In recent years, however, Autodesk has aggressively built up its in-house rendering expertise through acquisition and research. The results of those efforts are now starting to hit the market, in the form of two ray-tracing engines — one that’s embedded within the design workflow, and the other for standalone rendering projects.
Of the two new products mentioned, the first one - "Autodesk Raytracer" - was apparently actually developed in-house,
not being the direct result of Autodesk acquiring existing technology, unlike the second one, "VRED"...