I think that brake outer USED to be different because there was a danger of terminal failure of gear cable due to higher forces exerted when braking
I’m not sure that this has changed
I don’t see that ad suggesting both – I think Parkers have a section of their site called “cable – brake & gear” under which they sell both types
(mind, when I was in the US a shop tried to sell me gear outer for my brake and insisted it was the same stuff so maybe it now is. I went elsewhere and got normal, coiled brake outer)
I started a thread about brake outer a bit ago here but nobody seemed to know much about shimano’s range