head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Rhythmic target-locking down fixed rails with learnable scoring routes.

Execution · Practiced Mastery
One-thumb tap-timing precision over fixed courses with solvable coin routes.
Rez Infinite leans Execution (Practiced Mastery); Super Mario Run leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Rez Infinite
Target locking on rhythm carries the score chase
Super Mario Run
One-handed tap timing for coin lines demands precision
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Rez Infinite
Rail enemies are fully scripted
Super Mario Run
Auto-runner with no adaptive opponent; Toad Rally is asynchronous
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Rez Infinite
Fixed sequences - nothing random after one run
Super Mario Run
Courses are fixed and fully learnable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Rez Infinite
Scoring routes and chain patterns are learnable per area
Super Mario Run
Routing perfect coin runs is a solvable layout puzzle
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.