HDTV formats (720 x 1280 or 1080 x 1920 digital frames) are not anamorphic because they don't change the shape of the signal when storing it. DVDs are ALL anamorphic because all the video images stored in them are squeezed or streched into a 1.5 wide digital frame (NTSC DVD 480 x 720) or a 1.25 wide digital frame (PAL DVD 576 x 720).

You might say that they are ALL anamorphic. Some companies still indicate a Blu-ray as anamorphic but that's just for show.