Does this answer your question: (compliments of wikipedia)
VR Mode (aka Video Recording): This is a new format that allows editing/deleting titles and getting the total of space of deleted titles back/recording of copy once broadcasts/defect management. Used by DVD-RAM (DVD-RAM only uses this format) and DVD-RW. Because it is a newer format (well been around for several years but newer than DVD Video) it will only playback in modern DVD Players that support it.
Video mode This is the standard DVD Video mode format, the same format DVD films come in. Because the DVD Video format was invented before DVD’s were recordable it doesn’t allow editing on the disc, doesn’t support defect management (so not as robust for continuous everyday recording and wiping), if you delete a title you may not get the space back without completely erasing the disc, and needs a finalise step to play elsewhere. As it is the same format as commercial DVD films, there is a good chance it will work in most DVD Players. Can be used on DVD-RW and DVD-R discs, never used DVD-RAM. Most (but not all) recorders that use DVD-RW will give you choice of VR mode or Video mode.