Subsonic bullets are affected vertically by air friction against the rifling marks to a much greater extent than supersonic bullets, which have a shock wave that minimizes air flow along the parallel body of the bullet and the "fins" created from rifling.
Exception: Bullets, like barely supersonic .22LR high speed bullets that, as they slow down between muzzle and target, pass through the supersonic>subsonic transition zone, which causes them to deflect horizontally about 1/3 more than bullets that either stay supersonic, or start as subsonic rounds.
People are like rifles. Some are tried and true, having great eyes, personality, and fun to be with. Others never seem to hit the mark with you. Still others go off half-cocked. Still, it's nice to know most of them.