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

Execution · Pure Mechanics
Pure aim and movement skill tested against adaptive human opponents competing for spawn-cycle dominance.

Execution · Pure Mechanics
A fast arena shooter where twitch aim and movement against human opponents is everything.
Quake III Arena leans Execution (Pure Mechanics); Unreal Tournament 2003 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.
Quake III Arena
Rail and rocket aim at speed is the entire game
Unreal Tournament 2003
aim and movement speed decide duels
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Quake III Arena
Human opponents adapt their routes and timings in direct response
Unreal Tournament 2003
predicting human opponent positioning
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Quake III Arena
Spawn locations have mild randomness but are quickly mapped
Unreal Tournament 2003
weapon and pickup spawns vary
Quake III Arena leans a little harder on optimization, though the gap is small.
Quake III Arena
Armor and weapon timing routes are learnable and highly leveraged
Unreal Tournament 2003
map control and item timing solvable
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.