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 · Competitive PvP
A tactical shooter where precise gunplay against human opposition is the deciding skill.

Execution · Competitive PvP
Tests arena-shooter aim and map-control prediction against human lobbies.
Counter-Strike: Condition Zero leans Execution (Competitive PvP); Halo 2: Anniversary leans Execution (Competitive PvP).
Counter-Strike: Condition Zero leans a little harder on execution, though the gap is small.
Counter-Strike: Condition Zero
aim and spray control decide duels
Halo 2: Anniversary
Aim, grenades and movement decide every multiplayer duel
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
predicting human opponent positioning
Halo 2: Anniversary
Predicting human positioning and power-weapon pushes is constant
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
buy-round economy and drops vary slightly
Halo 2: Anniversary
Static spawns and timers leave little true randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
economy management and utility usage solvable
Halo 2: Anniversary
Weapon timers, map control and campaign routes are learnable systems
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.