He makes far more interceptions, tackles, clearances, blocks. He's more physical, wins more aerial duels and is a better marker. I like Stones but the only area I can tell where he beats Mangala is passing. Stones doesn't need to do as much of that other stuff as other CB's because he has Otamendi next to him, who does a frankly ridiculous amount of it. Stones has a lot of strengths to his game (and is still improving) but I'm doubtful he'd be able to pocket Ibrahimovic the way Mangala did.