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

Execution · Competitive PvP
Modern-military 64-player shooter where squads, commanders, and vehicles contest sprawling conquest maps.

Execution · Competitive PvP
Tactical gunfights testing aim, entry planning and prediction of human opponents online.
Battlefield 2 leans Execution (Competitive PvP); Tom Clancy's Rainbow Six: Vegas leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 2
Aim, jet and chopper piloting, infantry movement
Tom Clancy's Rainbow Six: Vegas
Aim and snap-to-cover gunplay punish slow hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 2
Squads and commanders out-maneuver human opposition
Tom Clancy's Rainbow Six: Vegas
Multiplayer angles and pushes demand reading human opponents
Battlefield 2 leans a little harder on variance, though the gap is small.
Battlefield 2
Spawn timing and vehicle contention add noise
Tom Clancy's Rainbow Six: Vegas
Terrorist hunt spawns vary modestly between runs
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 2
Flag rotation, class roles, and commander assets
Tom Clancy's Rainbow Six: Vegas
Room-entry planning and map knowledge 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.