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
Tests off-road handling and freeform route choice across an enormous open map.

Execution · Practiced Mastery
Wrangling high-speed 3D movement through fixed stages and boss scripts.
Fuel leans Execution (Pure Mechanics); Sonic Adventure DX: Director's Cut leans Execution (Practiced Mastery).
Fuel leans a little harder on execution, though the gap is small.
Fuel
Off-road vehicle control through weather events is the core test
Sonic Adventure DX: Director's Cut
High-speed 3D control and jank-wrangling demand real hands
Fuel leans a little harder on reads, though the gap is small.
Fuel
AI racers rubber-band on scripts; online is thin
Sonic Adventure DX: Director's Cut
Chaos bosses run fixed phase scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fuel
The huge map is scripted-but-unknown until explored
Sonic Adventure DX: Director's Cut
Stage layouts and upgrades never change
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fuel
Route choice across open terrain rewards planning
Sonic Adventure DX: Director's Cut
Speedrun routing and A-rank paths are learnable systems
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.