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

Execution · Pure Mechanics
WWII gunfight execution with light multiplayer prediction.

Execution · Pure Mechanics
Party-sized motion-timing contests with learnable per-event techniques.
Call of Duty 3 leans Execution (Pure Mechanics); Mario & Sonic at the Olympic Winter Games leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Aimbot trivialises both campaign and multiplayer gunfights
Mario & Sonic at the Olympic Winter Games
Motion-timing and button precision decide every event
Call of Duty 3 leans a little harder on reads, though the gap is small.
Call of Duty 3
Multiplayer adds modest human positional prediction
Mario & Sonic at the Olympic Winter Games
Local human rivals add mild prediction in head-to-head events
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Scripted setpieces and spawn flow add minor unknowns
Mario & Sonic at the Olympic Winter Games
Events are fixed; minor physics wobble
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Map knowledge and weapon choice reward light study
Mario & Sonic at the Olympic Winter Games
Each event has a learnable optimal technique
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.