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 · Pure Mechanics
A fast-paced military shooter where twitch aim against other players is the core test.

Execution · Pure Mechanics
Momentum-perfect platform racing spiced with item mind games against humans.
Call of Duty: Modern Warfare 3 leans Execution (Pure Mechanics); SpeedRunners leans Execution (Pure Mechanics).
Call of Duty: Modern Warfare 3 leans a little harder on execution, though the gap is small.
Call of Duty: Modern Warfare 3
aim and reflexes decide most engagements
SpeedRunners
Grapple swings and boost timing at full speed decide races
Call of Duty: Modern Warfare 3 leans a little harder on reads, though the gap is small.
Call of Duty: Modern Warfare 3
predicting human opponent positioning and habits
SpeedRunners
Timing item throws against human racers' habits wins exchanges
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 3
spawn placement and loadout drops vary
SpeedRunners
Item pickups add party-game chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 3
loadout tuning and map knowledge help
SpeedRunners
Optimal racing lines per track 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.