DVI or Digital Visual Interface is used to make a connection between a video source and a display device (such as a television or a computer monitor) to play a video. DVI and Dual-link DVI can be differentiated from each other just by looking at the pin. The pin on the connector of a single DVI has 2 distinct blocks on one side with a gap while the dual-link DVI has just a single block of pins where the gap is filled in.
With their visual clarity and capacity, the single link DVI can support a maximum bandwidth of 165 MHz (1280x1024 at 85 Hz and 1920x1080 Hz at 60 Hz) while the dual-link DVI supports up to 2x165 MHz (2048x1536 at 60 Hz and 1920x1080 at 85 Hz).
If in case you are feeling confused between the two, you should remember that the DVI single link comes with one conductor while the DVI dual-link will come with dual conductors. Some people may confuse the DVI dual-link with the dual-display, but you should remember that these two are different from each other two.
The dual display will have the ability to show two different images at the same time. The DVI dual-link is used interchangeably with the HDMI because they would have the ability to offer the same video signal. The only difference between the two is that the DVI dual-link will not come with audio.