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
Free-to-play objective shooter from Splash Damage with mercenary classes.
Counter-Strike: Condition Zero leans Execution (Competitive PvP); Dirty Bomb 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
Dirty Bomb
Fast strafing gunfights and ability timing need quick hands
Counter-Strike: Condition Zero leans a little harder on reads, though the gap is small.
Counter-Strike: Condition Zero
predicting human opponent positioning
Dirty Bomb
Human teams adapt pushes around objective chokepoints
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
Dirty Bomb
Fixed maps and abilities, minor loadout-card 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
Dirty Bomb
Merc compositions and objective timings reward planning
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.