A Network Video Recorder (NVR) is used to record video footage in a digital format to a hard disk drive (HDD). It usually captures video/images through an ethernet network via Cat5 or Cat6 cables from IP cameras. It is mostly used for physical security applications. A combination of an NVR and IP cameras is more expensive, however, but it offers much higher resolution and superior video clarity when compared to a DVR & analog cameras. Some IP cameras offer up to 5 mega pixels in resolution. Proximity is not an issue and the IP cameras can be located anywhere as long as they can be accessed through a network.
DVR - Digital Video Recorder
A Digital Video Recorder (DVR) is used to record video footage in a digital format to a hard disk drive (HDD). It usually captures video/images through coaxial cables from analog cameras. It is usually used for physical security applications. This combination is more cost effective and easier to setup, however the resolution is usually limited to D1 (720×480). Proximity is a limitation as the analog cameras cannot be more than 700-1000 feet away from the DVR without visible degradation in video quality.
HVR - Hybrid Video Recorder
A Hybrid Video Recorder (HVR) is used to record video footage in a digital format to a hard disk drive (HDD). It accommodates both IP and analog cameras and captures video/images through an ethernet network via Cat5 / Cat6 cables from IP cameras as well as coaxial cables from analog cameras. It is mostly used for physical security applications. This option is a good choice when planning for future expansion into an IP video surveillance system as your existing analog cameras can be reused and incorporated into the system without any drop in coverage.