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 · Practiced Mastery
MMO street racing testing driving lines plus grindable car-build advantage.

Execution · Pure Mechanics
Party racing and arena shootouts decided mostly by platforming speed.
Need for Speed: World leans Execution (Practiced Mastery); Rayman Arena 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.
Need for Speed: World
Racing lines, drift control and pursuit evasion reward clean hands
Rayman Arena
Footrace platforming speed and arena aim decide matches
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Need for Speed: World
Human rivals in lobbies add slight positional prediction
Rayman Arena
Human rivals add light jockeying, little depth
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Need for Speed: World
Pursuit spawns and lobby skill add mild noise
Rayman Arena
Minor pickup randomness in arenas
Need for Speed: World leans a little harder on optimization, though the gap is small.
Need for Speed: World
Car builds, powerups and route knowledge compound advantage
Rayman Arena
Track knowledge gives a modest edge
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.