head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Execution · Practiced Mastery
343's debut pits Master Chief against the Didact with loadout-driven multiplayer.

Execution · Practiced Mastery
A modern-war reboot following Tier 1 operators in Afghanistan.
Halo 4 leans Execution (Practiced Mastery); Medal of Honor (2010) leans Execution (Practiced Mastery).
Halo 4 leans a little harder on execution, though the gap is small.
Halo 4
Precision aim amid faster kill times
Medal of Honor (2010)
Modern gunplay in campaign and multiplayer
Halo 4 leans a little harder on reads, though the gap is small.
Halo 4
Human opponents in Infinity multiplayer
Medal of Honor (2010)
Competitive MP adds human prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 4
Ordnance drops randomise mid-match rewards
Medal of Honor (2010)
Scripted campaign, modest MP randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 4
Loadout building and map control
Medal of Honor (2010)
Loadouts and map control are learnable
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.