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
The 32-bit X series highlight where Zero becomes fully playable with his own saber-based campaign.

Execution · Practiced Mastery
Open-world reboot of Mirror's Edge centered on free-running across the city of Glass.
Mega Man X4 leans Execution (Practiced Mastery); Mirror's Edge Catalyst 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 X4
Dash-jump mobility and Zero's saber combos test hands
Mirror's Edge Catalyst
Flow-state parkour with timing-based combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X4
Mavericks follow fixed scripts
Mirror's Edge Catalyst
Enemies are scripted obstacles
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X4
Upgrade capsule locations hidden initially
Mirror's Edge Catalyst
Open world is static once explored
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man X4
Armor parts, weakness order, and X-vs-Zero routing
Mirror's Edge Catalyst
Time trials reward optimal route discovery
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.