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
Analog-stick boxing testing punch precision and counter-baiting against human opponents.

Execution · Competitive PvP
Tactical gunfights testing aim, entry planning and prediction of human opponents online.
Fight Night 2004 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.
Fight Night 2004
Analog punch control and block timing are the core test
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.
Fight Night 2004
Versus humans, baiting counters and feinting is genuine prediction
Tom Clancy's Rainbow Six: Vegas
Multiplayer angles and pushes demand reading human opponents
Tom Clancy's Rainbow Six: Vegas leans a little harder on variance, though the gap is small.
Fight Night 2004
Outcomes follow inputs with little randomness
Tom Clancy's Rainbow Six: Vegas
Terrorist hunt spawns vary modestly between runs
Tom Clancy's Rainbow Six: Vegas leans a little harder on optimization, though the gap is small.
Fight Night 2004
Stat training and stamina management add a planning layer
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.