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

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

Execution · Pure Mechanics
Keeping speed through destruction-racing chaos that punishes clean-lap plans.
Blur leans Execution (Pure Mechanics); FlatOut: Ultimate Carnage 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.
Blur
Racing lines and dodging shots demand car control
FlatOut: Ultimate Carnage
Holding racing lines through wrecks and ragdoll chaos tests hands
Blur leans a little harder on reads, though the gap is small.
Blur
Human racers bait and time power-ups against you
FlatOut: Ultimate Carnage
Rival drivers ram predictably, light multiplayer jockeying
Blur leans a little harder on variance, though the gap is small.
Blur
Power-up pickups and incoming attacks add chaos
FlatOut: Ultimate Carnage
Debris and pileups scramble any planned lap
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
FlatOut: Ultimate Carnage
Car upgrades and track shortcuts are mappable
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.