Difference in sound between copper and silver digital cables?

As the French chef says "No diffawrance!" - BITS IS BITS!

Ideologues kindly butt out with your ill-informed opinions.

Yes, there is a difference, but it largely comes from the implementation. There are copper conductors, silver, and copper coated or copper infused with silver. The design and material used in the  dialectric also contributes to sonics.