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
Punk action game about an otaku assassin climbing a ranked killer leaderboard.

Execution · Practiced Mastery
Third-person action where Captain Titus chainswords through ork hordes without a cover system.
No More Heroes leans Execution (Practiced Mastery); Warhammer 40,000: Space Marine 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.
No More Heroes
Beam katana clashes and wrestling throws with motion timing
Warhammer 40,000: Space Marine
Melee-shooting flow and execution timing carry combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
No More Heroes
Assassins are scripted boss fights
Warhammer 40,000: Space Marine
Ork hordes follow scripted aggression
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
No More Heroes
Deterministic encounters
Warhammer 40,000: Space Marine
Encounters are fixed and predictable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
No More Heroes
Boss pattern learning and money grinding
Warhammer 40,000: Space Marine
Weapon choice and fury management are simple to learn
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.