Some weight distribution systems like Equalizer also have sway control built into the design, some are simply weight distribution and you need to add on a sway control bar.
That said if you fishtail down the road then you have something fundamentally wrong and need to fix that BEFORE adding weight distribution/anti-sway as those systems should help with occasional problems like bow wake from a passing semi or a sudden gust, not try to correct for problems like too little tongue weight or overloaded rear axle tires.
2019 Dutchman Kodiak 293RLSL
2015 GMC 1500 Sierra 4x4 5.3 3.42 full bed
Equalizer 10k WDH