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
Moody Halo side story about ordinary troopers piecing together a night in New Mombasa.

Execution · Practiced Mastery
Co-op action take on Resident Evil trading dread for set-piece gunfights.
Halo 3: ODST leans Execution (Practiced Mastery); Resident Evil 5 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.
Halo 3: ODST
Squishier soldier demands careful aim and positioning
Resident Evil 5
Action-heavy aiming and melee timing carry encounters
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 3: ODST
Covenant patrols are scripted, not adaptive
Resident Evil 5
Co-op coordination, not adversarial prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 3: ODST
Open Mombasa hides clues until found
Resident Evil 5
Mostly fixed encounters after first run
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 3: ODST
Firefight wave knowledge and route planning
Resident Evil 5
Weapon upgrades and Mercenaries routing reward planning
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.