The Brovira and Portriga formulas were very close together. They both used bromide, chloride and iodide in making a simple emulsion. The big difference seems to have been the curve shape, as the tones of the two silver images would be very similar. This would place both of them in the same category of Kodabromide paper from Kodak.
And yet..the "look" of the prints are radically different between Portriga and Brovira of the same period..also the keeping and ageing qualities are different. The unexposed Portriga keeps better over the years. I have boxes of Portriga and Brovira purchased together, kept together, probably late 1970's, and the Portriga is just fine (a little Liquid Orthazite in the developer to minimize age fog), but the Brovira does not seem to be generally salvagable.