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
The N64 entry whose boost-or-survive health gamble layers routing decisions onto raw speed control.

Execution · Practiced Mastery
Twitch dodging and shooting over fully memorisable enemy wave patterns.
F-Zero X leans Execution (Pure Mechanics); Star Soldier leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
F-Zero X
Sixty-frame control of thirty machines at top speed
Star Soldier
Dodging dense fire and rapid shooting carry every run
F-Zero X leans a little harder on reads, though the gap is small.
F-Zero X
Rival AI is non-adaptive
Star Soldier
Enemy waves are identical scripted formations
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
F-Zero X
X Cup random tracks are a minor mode
Star Soldier
Nothing random once spawn patterns are learned
Star Soldier leans a little harder on optimization, though the gap is small.
F-Zero X
Boost-health tradeoffs and shortcuts reward routing
Star Soldier
Memorising waves and power-up routes defines high scores
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.