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 · Practiced Mastery
A story-driven skateboarding game still won by trick execution.

Execution · Pure Mechanics
Futuristic sequel to the Trials physics-bike series with FMX tricks and brutally precise tracks.
Tony Hawk's Underground leans Execution (Practiced Mastery); Trials Fusion leans Execution (Pure Mechanics).
Trials Fusion leans a little harder on execution, though the gap is small.
Tony Hawk's Underground
Combos plus off-board tricks keep the input ceiling high
Trials Fusion
Frame-tight balance and throttle inputs
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Tony Hawk's Underground
Story missions are scripted, not adaptive
Trials Fusion
No adaptive opposition
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Tony Hawk's Underground
Fixed levels and mission scripts
Trials Fusion
Deterministic physics, known tracks
Tony Hawk's Underground leans a little harder on optimization, though the gap is small.
Tony Hawk's Underground
Mission and score-line routing remain solvable
Trials Fusion
Optimal lines and trick scoring are learnable
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.