In addition to rendering to the 3ds Max Rendered Frame Window (RFW or VFB), V-Ray allows you to render to a V-Ray specific frame buffer, which has some additional capabilities:
* Allows you to view all render elements in a single window and switch between them easily;
* Keeps the image in full 32-bit floating-point format
* Allows you to perform simple color corrections on the rendered image;
* Allows you to choose the order in which the buckets are rendered.
The V-Ray VFB alos has some limitations, which are listed in the Notes section below.