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

Execution · Pure Mechanics
Arcade racing with Mario Kart-style power-ups bolted onto licensed cars.

Execution · Pure Mechanics
An action racer where players detonate the environment itself to wreck rivals and reroute the track.
Blur leans Execution (Pure Mechanics); Split/Second leans Execution (Pure Mechanics).
Split/Second leans a little harder on execution, though the gap is small.
Blur
Racing lines and dodging shots demand car control
Split/Second
Drafting, drifting and dodging collapsing set pieces.
Blur leans a little harder on reads, though the gap is small.
Blur
Human racers bait and time power-ups against you
Split/Second
Timing powerplays against human rivals rewards prediction.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Blur
Power-up pickups and incoming attacks add chaos
Split/Second
Triggered explosions and route changes upend races constantly.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Blur
Track knowledge and pickup routes are learnable
Split/Second
Knowing every trap and shortcut converges with play.
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.