A DVR (Digital Video Recorder) is a standalone recorder that is compatible with any camera that has a BNC input, offering almost universal camera compatibility. A DVR uses a Linux-based system, and is typically lower in price than an NVR (Network Video Recorder). A DVR is connected to your network so you can view the video over the internet or on a smart phone; all the cameras are installed on a CCTV system.
An NVR (Network Video Recorder) can receive video from multiple IP Cameras and record them in one central place over a CAT5 network cable. An NVR system is typically installed on PCs or servers, and are designed and built according to the number of cameras, resolution of the cameras, and frame rate you choose. It is critical to ensure that the NVR is compatible with your IP Cameras. (IP Cameras are not necessarily interchangeable like cameras on a CCTV system.)
A hybrid system is a custom-designed system that accepts both analog and IP Cameras. These systems are good for customers who already have a number of analog cameras and are migrating toward IP Cameras. These systems can be PC or Linux-based, depending on the manufacturer. Like an NVR system, it important to make sure that the hybrid system you install is compatible with the IP cameras you purchase.