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
Chess-style positioning where every capture becomes an action duel you must win by hand.

Execution · Competitive PvP
Tactical gunfights testing aim, entry planning and prediction of human opponents online.
Archon leans Execution (Practiced Mastery); Tom Clancy's Rainbow Six: Vegas leans Execution (Competitive PvP).
Tom Clancy's Rainbow Six: Vegas leans a little harder on execution, though the gap is small.
Archon
Contested squares resolve in real-time arena combat you must pilot
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.
Archon
Human opponents bait piece trades and combat habits
Tom Clancy's Rainbow Six: Vegas
Multiplayer angles and pushes demand reading human opponents
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Archon
Luminosity cycle is fully visible; little hidden information
Tom Clancy's Rainbow Six: Vegas
Terrorist hunt spawns vary modestly between runs
Archon leans a little harder on optimization, though the gap is small.
Archon
Chess-like positioning and piece matchups reward calculated play
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.