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

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

Execution · Pure Mechanics
Multiplayer-focused Halo with the series' highest movement skill ceiling.
Counter-Strike: Condition Zero leans Execution (Competitive PvP); Halo 5: Guardians leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Counter-Strike: Condition Zero
aim and spray control decide duels
Halo 5: Guardians
Thrusters, clamber, and aim raise the ceiling
Counter-Strike: Condition Zero leans a little harder on reads, though the gap is small.
Counter-Strike: Condition Zero
predicting human opponent positioning
Halo 5: Guardians
Arena ranked play is human-versus-human
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 5: Guardians
Spawns and REQ Warzone 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 5: Guardians
Movement routes and weapon timers
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.