The dual shield Rg6 and quad shield Rg6 cables themselves are exactly the same, but the Quad shield housing offers more protection against static inference than the standard Rg6 cable. In instances in which there should be little to no signal interference, a dual shield Rg6 will work just as well as the Rg6 Quad shield.
The Rg6 Dual shield and Rg6 Quad shield are coaxial cables. An Rg6 coaxial cable is the standard choice for transferring digital and radio frequencies.
The extra layers of protection from frequency interference also impact what each cable will be used for. Dual shield Rg6 cables, for example, will be commonly found inside residential homes, while quad shield cables would be commonly used for military applications.