Generally speaking, VGA and DVI connectors are both powerful tools in terms of transmitting video from a source, fro example, a computer or tablet, to a display device, like a monitor, TV or projector. As a matter of fact, the main difference between VGA and DVI lies in how the video signal travels. In effect, VGA connectors and cables are able to carry analog signals while DVI can carry both analog and digital signals. In comparison, DVI is a newer technology which is capable of offering people better and sharper display. Fortunately, it is easy for people to distinguish DVI and VGA as they have obvious physical difference: VGA connectors and ports are blue while DVI connectors are white.
On the other hand, DVI can offer a higher quality signal than VGA. The higher the resolution is, the more noticeable the difference will be. After all, the quality of the video depends on the operation mechanism and the length and quality of the cable.
However, the operation mechanism of VGA and DVI has no difference for users. Actually, they have no desire to understand the difference between them. For them, both connectors work in the same way: devices have female ports and the connectors have male endpoints.
In application, the operation of VGA and DVI has much difference which happens in the data transmission process. VGA connectors transmit analog signals. As a result, the digital video signal received from the source will be converted to analog signals in order to be transmitted via the cable. When the display device is an old CRT monitor, then it is able to accept the analog signal. However, the majority of display devices used today are digital. Therefore, the analog signal of the VGA connectors will be converted to digital signal in the end. In consequence, the video quality for VGA connectors will suffer some kind of degradation.