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

Execution · Practiced Mastery
Aggressive circuit racing testing car control over memorisable tracks and braking points.

Execution · Practiced Mastery
Tests reaction timing and memorised counter-patterns against scripted kung-fu opponents.
Race Driver: Grid leans Execution (Practiced Mastery); Yie Ar Kung-Fu leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Aggressive wheel-to-wheel car control is the core demand
Yie Ar Kung-Fu
Hit timing and spacing against fast opponents is the core
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Online racing adds light opponent positioning awareness
Yie Ar Kung-Fu
CPU foes use simple patterns; versus play is shallow
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Damage outcomes add slight unpredictability to contact
Yie Ar Kung-Fu
Opponent behaviour is near-deterministic once learned
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Race Driver: Grid
Braking points, lines and flashback management are learnable
Yie Ar Kung-Fu
Each foe has an exploitable pattern to memorise
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.