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
FPS aim welded to a team economy of base-destruction priorities.

Execution · Pure Mechanics
Console shooter execution across scripted set pieces and once-massive human multiplayer.
Command & Conquer: Renegade leans Execution (Practiced Mastery); Resistance 2 leans Execution (Pure Mechanics).
Resistance 2 leans a little harder on execution, though the gap is small.
Command & Conquer: Renegade
FPS aim in infantry and vehicle fights carries the game
Resistance 2
Weapon handling and boss dodging demand console-shooter precision
Resistance 2 leans a little harder on reads, though the gap is small.
Command & Conquer: Renegade
Multiplayer base assaults involve predicting human team pushes
Resistance 2
60-player multiplayer rewarded reading humans; campaign Chimera don't adapt
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Renegade
Maps and economy rules are fully known
Resistance 2
Campaign encounters are set pieces
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Renegade
Credit economy and building-target priority decide C&C-mode matches
Resistance 2
Exotic weapon choice and class co-op roles add planning
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.