from the description, the silverflex cables are all silver (i.e. "24 gauge Silver"), while the "silver-clad" cables that are popular here on ts.com are typically silver-plated copper conducters (i.e. copper conductors with silver on the outside). people say that the electrons travel on the outside of the wire anyway, so, in theory, the silver-clad cables have silver where the electrons are flowing, even if the whole cable isn't silver.
Does any of this make a difference? maybe. the more people you ask, the wider range of responses you'll get. Are silver cables better than silver-clad? only one way to find out which you prefer. (personally, I love the sound of my recording gear using regular Canare star-quad copper cables, so I haven't bother to "upgrade" to silver or silverclad mic cables)