I honestly think he has more potential.
He pretty much has every single skill Mackinnon has... Speed, Puck handling, shot, wild card ability, physical side. The one area he's maybe ever so slightly behind Mack in is that physical game. Neither guy uses it much but when Mack gets pissed off he can turn into an absolute bull in a china shop as the New Jersey Devils found out a couple weeks ago. Dude is a freight train and will lay the body if he's mad. Makar has thrown some big hits himself already in the NHL but I dont think he quite has that physical element Mack has when he lets loose.
However, the one major asset Makar has over Mack.... His brain. Makar thinks the game at about as high of a level as you can possibly think it. Mackinnon isn't on that level.
It's Cales brain, combined with the speed and skill he has that leads me to truly believe if everything comes together for him like it has with Mack, that he ends up an even better player. Like, 2-3 time Norris trophy winner, first ballot Hall of Fame type of upside in his game. The fact he's on pace to have a rookie season not matched in 30 years for a Dman speaks to the kind of skill and upside he has.