Not much. Allegedly, the Salmon Rouge was the commercial name used by one of the former Coticule manufacturers to sell a particular type of fast BBW. From what little I have heard about them, they were the only BBW's that were separately sold as stones for honing. Other BBW's were only used as backing stone, glued to Coticules. They were not meant to be used for honing.
That's why I assumed that, if yours is a BBW, it could very well be one of the old Salmon Rouge hones. Without a box or a label, I can never know for sure. I have only read and heard about the BBW called "Salmon rouge". Never actually seen one.