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
A linear western shooter testing aim and learned encounter pacing through scripted set pieces.

Execution · Pure Mechanics
A late-90s mercenary FPS infamous for its graphic locational damage system.
Call of Juarez: Bound In Blood leans Execution (Practiced Mastery); Soldier of Fortune leans Execution (Pure Mechanics).
Soldier of Fortune leans a little harder on execution, though the gap is small.
Call of Juarez: Bound In Blood
Aimbot would trivialise the gunfights and showdown duels
Soldier of Fortune
Fast twitch aim against fragile enemies decides everything
Soldier of Fortune leans a little harder on reads, though the gap is small.
Call of Juarez: Bound In Blood
Scripted campaign enemies; thin multiplayer adds little prediction
Soldier of Fortune
Multiplayer duels add a little human prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Juarez: Bound In Blood
Encounter layouts are unknown on first run, then fixed
Soldier of Fortune
Campaign layouts and spawns are fixed
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Juarez: Bound In Blood
Cover routes and concentration-mode usage are learnable patterns
Soldier of Fortune
Weapon choice and level routes are quickly learned
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.