head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Practiced Mastery
Executing memorised high-speed routes through deterministic platforming levels.

Execution · Practiced Mastery
A test of 3D movement control with a deep routing layer underneath.
Sonic Generations leans Execution (Practiced Mastery); Super Mario 64 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.
Sonic Generations
Holding speed through precise jumps and boosts is the test
Super Mario 64
Perfect analog inputs trivialise precise jumps, dives and wall-kicks
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Sonic Generations
No opponent; bosses are fixed patterns
Super Mario 64
Solo platformer - no adaptive opponent anywhere
Super Mario 64 leans a little harder on variance, though the gap is small.
Sonic Generations
Levels are fully deterministic
Super Mario 64
Star locations and level layouts are fixed once seen
Sonic Generations leans a little harder on optimization, though the gap is small.
Sonic Generations
S-ranks come from memorising optimal routes and shortcuts
Super Mario 64
Star routing and movement tech form a deep solvable layer
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.