As stated above NVOD = Near video on demand. These channels were broadcast to everybody at set intervals. You picked an event at a certain time and then were authorised to view that event. This technology has efectively been made obsolete by the new VOD system although a few events (usually sporting type) will continue to use the system
VOD = Video on demand is a new technology where you pick the time you want to view something. You decide what you want to watch and then book the event. You are then in total control of that stream with the ability to fast forward/fast rewind/pause/stop etc just as though you had a DVD playing. Tha actual data stream is not broadcast but is routed to the particular network node where the order originated. This allows bandwidth to be allocated on a per node basis.