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 · Practiced Mastery
A kart racer with an adventure structure and three vehicle types, lighter on item chaos than its rivals.

Execution · Pure Mechanics
Keeping speed through destruction-racing chaos that punishes clean-lap plans.
Diddy Kong Racing leans Execution (Practiced Mastery); 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.
Diddy Kong Racing
Drift boosts across car, hovercraft and plane demand precision.
FlatOut: Ultimate Carnage
Holding racing lines through wrecks and ragdoll chaos tests hands
FlatOut: Ultimate Carnage leans a little harder on reads, though the gap is small.
Diddy Kong Racing
Multiplayer item duels add mild prediction; AI is scripted.
FlatOut: Ultimate Carnage
Rival drivers ram predictably, light multiplayer jockeying
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diddy Kong Racing
Balloon pickups and items inject moderate randomness.
FlatOut: Ultimate Carnage
Debris and pileups scramble any planned lap
Diddy Kong Racing leans a little harder on optimization, though the gap is small.
Diddy Kong Racing
Vehicle choice, balloon upgrade routes and boss strategies converge.
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.