Actually Silver solder is a soft solder (you can buy it at any HW store), that contains a small amount of Silver (2% Ag + Sn,Bi,Cu...) and melts around 440F.
Silver brazing alloys contain a lot more Silver (like 72% Ag, 28 %Cu) and melts at a significantly higher Temp possibly up to 1600F.
It's a lot stronger, and a lot more expensive.

Best regards,
WC-