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 · Competitive PvP
Cold War-era shooter pairing twitch multiplayer with the cult Zombies mode.

Execution · Competitive PvP
The peak-era Konami football game prized for weighty, skill-driven match play.
Call of Duty: Black Ops leans Execution (Competitive PvP); Pro Evolution Soccer 6 leans Execution (Competitive PvP).
Call of Duty: Black Ops leans a little harder on execution, though the gap is small.
Call of Duty: Black Ops
Gunfights hinge on aim and reaction speed
Pro Evolution Soccer 6
First touch, through balls, and dribbles demand precise control
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Black Ops
Reading human opponents' positioning and timing
Pro Evolution Soccer 6
Versus matches are constant feint and positioning prediction
Call of Duty: Black Ops leans a little harder on variance, though the gap is small.
Call of Duty: Black Ops
Spawns, care packages, zombies RNG
Pro Evolution Soccer 6
Deflections and keeper spills add light randomness
Call of Duty: Black Ops leans a little harder on optimization, though the gap is small.
Call of Duty: Black Ops
Class builds, map control, zombies routing
Pro Evolution Soccer 6
Formations and player roles are studyable
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.