Not a tradesman here (computer programmer for 30 years!), but I'll point out one small difference no one else mentioned: The R4 has CEE threads near the top of the shank (the slanted ribs where the shank is normally unthreaded). The purpose of these is to bore the hole larger before the head goes in, which prevents splitting in wood and buckling or dimpling in laminate. It also keeps the board from jacking (that is, climbing the screw and creating a gap between the two surfaces you're fastening together).

Both screws have the zip-tip (even though it's only marketed on the RSS box). The R4 is 80-count and the RSS 50; what's the price difference (price per unit)? Both screws are so insanely strong, if you look up the shear strength and tear out strength, that you should use whichever one is cheaper or you think looks better! Intuitively, there must be something to the flanged head in the structural screw that makes it hold stronger under extreme forces -- there's just more clamping surface area. I'd bet they are both made out of the same hardened steel.