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 PS1 third-person espionage shooter following agent Gabe Logan against a viral terror plot.

Execution · Practiced Mastery
A 1998 single-player sci-fi shooter exploring an alien planet with agile enemies.
Syphon Filter leans Execution (Practiced Mastery); Unreal 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.
Syphon Filter
Taser duels and headshots under pressure test the hands
Unreal
Aim and dodging against fast Skaarj carry encounters
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Syphon Filter
Terrorist AI is scripted spawns and patterns
Unreal
Scripted alien AI never adapts to you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Syphon Filter
Minor first-run uncertainty in enemy placements
Unreal
First-run level surprises map out quickly
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Syphon Filter
Memorizing levels and weapon stashes makes runs routine
Unreal
Weapon choice, secrets, and route knowledge trivialise replays
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.