There's no universal standard. Every manufacturer uses different terms. So one maker's Silvertip might be like another maker's Super.
If it's the same manufacturer, than the Super Silvertip is probably whiter in the tips. Are you talking about Rooney brushes here? Rooney has both a Silvertip and Super Silvertip grade. They're very similar, though the Super is a bit whiter.
See the Vintage Blade discussion here: http://www.vintagebladesllc.com/vshop/xcart/home.php?cat=152