head to head
Neither is simply harder - they are hard in different places. Mario Kart 64 demands more execution; Pummel Party demands more variance.

Execution · Twitch Chaos
N64 couch classic where blue shells and shortcuts decide friendships.

Variance · Pure Chaos
A board-game party title where dice luck and item variance swing outcomes far more than any individual skill.
Mario Kart 64 leans Execution (Twitch Chaos); Pummel Party leans Variance (Pure Chaos).
Mario Kart 64 leans clearly harder on execution.
Mario Kart 64
Mini-turbo snaking and shortcut execution
Pummel Party
Mini-game inputs vary but most are forgiving over short windows
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart 64
Couch rivals bait shells and fakes
Pummel Party
Light reads on human opponents in board and mini-games
Pummel Party leans clearly harder on variance.
Mario Kart 64
Item draws swing every race
Pummel Party
Dice rolls, item draws, and board events dominate outcome variance
Mario Kart 64 leans a little harder on optimization, though the gap is small.
Mario Kart 64
Shortcut and line knowledge is fully mapped
Pummel Party
Item usage timing and board routing have learnable edges
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.