The primary distinguishing factor of PTZ cameras, as the designation implies, is remote control of camera movement and zoom.  Some PTZ cameras also feature an auto-track function that will sense an area in the frame that is substantially different in luminance from the background and will activate the pan and tilt to allow the camera to keep that area in frame as it moves Another spec that many PTZ cameras share is digital and optical zoom capability. As with any video camera with such features, the optical zoom does not noticeably diminish image quality.  Now, the Internet and IP control have allowed some of these devices to extend their range from around the building to across the planet.