head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Mid-demand 3D platforming execution across fixed gravity puzzles.

Execution · Practiced Mastery
A Serious Sam-style horde shooter testing strafing aim against scripted waves.
Super Mario Galaxy leans Execution (Practiced Mastery); Will Rock 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.
Super Mario Galaxy
Gravity-bending jumps need timing, though forgiving by Mario standards
Will Rock
Circle-strafing huge enemy swarms is the whole test
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Super Mario Galaxy
Bosses repeat fixed patterns - nothing adapts
Will Rock
Monsters charge in fixed spawned waves
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Super Mario Galaxy
Galaxies are scripted; surprises evaporate after one visit
Will Rock
Spawns are scripted and repeat identically
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Super Mario Galaxy
Star routes and comet challenges reward learned solutions
Will Rock
Weapon choice and arena positioning 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.