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
Tight platforming execution against fixed boss patterns with a solvable upgrade route.

Execution · Practiced Mastery
A story-driven skateboarding game still won by trick execution.
Mega Man X3 leans Execution (Practiced Mastery); Tony Hawk's Underground 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.
Mega Man X3
Dash-jump precision and boss dodging demand tight inputs
Tony Hawk's Underground
Combos plus off-board tricks keep the input ceiling high
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X3
Mavericks cycle fixed attack patterns
Tony Hawk's Underground
Story missions are scripted, not adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X3
Nothing random - every pickup and enemy is placed
Tony Hawk's Underground
Fixed levels and mission scripts
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X3
Weapon-order and upgrade routing is a known solved sequence
Tony Hawk's Underground
Mission and score-line routing remain solvable
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.