head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Pure Mechanics
A minimalist top-down rally racer testing commitment, rhythm and clean car control.

Execution · Pure Mechanics
First-person physics platformer about leaping across a convoy of crashing trucks.
Art of Rally leans Execution (Pure Mechanics); Clustertruck 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.
Art of Rally
Minimalist top-down physics demand precise committed corner entries
Clustertruck
Frame-tight jumps across moving trucks
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Art of Rally
Time-attack format; no adaptive opponent
Clustertruck
No opponent
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Art of Rally
Surface grip variation and weather add mild variance
Clustertruck
Physics chaos makes truck piles unpredictable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Art of Rally
Rally car and service choices form a light solvable meta-layer
Clustertruck
Route lines and ability use for speedruns
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.