Digital CCTV cameras or IP (Internet Protocol) cameras record in a digital format which is sent to an NVR (Network Video Recorder) that must be connected to the same network.
Analog CCTV cameras send recorded images over a cable to DVR (Digital Video Recorders) who then convert the video to a digital format.
WhetherAnalog or IP, cameras come in a variety of styles. Each style excels at a specific use. Another thing to take into account is whether the camera is outdoor or indoor rated.