head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Practiced Mastery
Series finale blending stealth with active battlefields and heavy cinematics.

Optimization · Practiced Mastery
Planning stealth routes and psychic-power use through scripted guard patrols.
Metal Gear Solid 4: Guns of the Patriots leans Optimization (Practiced Mastery); Second Sight leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Gear Solid 4: Guns of the Patriots
flexible gunplay alongside sneaking
Second Sight
Aiming and psychic-power juggling under fire need moderate hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Gear Solid 4: Guns of the Patriots
battlefield factions act on scripts
Second Sight
Guard AI runs predictable patrol scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Gear Solid 4: Guns of the Patriots
mid-battle chaos mostly cosmetic
Second Sight
Patrol routes are unknown only on first pass
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Gear Solid 4: Guns of the Patriots
camo, gear, and route knowledge per act
Second Sight
Planning stealth routes and power usage solves each level
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.