S/PDIF refers to the signalling, not the conductor type.
Coaxial and TOSlink are both using S/PDIF
https://en.wikipedia.org/wiki/S/PDIF
Fiber has the advantage of never causing a ground loop, which can have odd effects in digital, which may or may not be audible as a traditional ground loop.
Some swear that copper sounds better, which could have something to do with the connector hardware/drivers.
I've long ago switched to USB.
Coaxial and TOSlink are both using S/PDIF
https://en.wikipedia.org/wiki/S/PDIF
Fiber has the advantage of never causing a ground loop, which can have odd effects in digital, which may or may not be audible as a traditional ground loop.
Some swear that copper sounds better, which could have something to do with the connector hardware/drivers.
I've long ago switched to USB.