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.

Reads · Light / Casual
Source-engine sandbox whose community modes range from building to social deduction.

Execution · Light / Casual
A shallow mashy wrestler where exploiting janky moves beats any deep skill.
Garry's Mod leans Reads (Light / Casual); The Simpsons Wrestling leans Execution (Light / Casual).
The Simpsons Wrestling leans a little harder on execution, though the gap is small.
Garry's Mod
Varies by mode; base sandbox is undemanding
The Simpsons Wrestling
Mashy controls with little precision to reward
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Garry's Mod
Social deduction modes like TTT involve humans
The Simpsons Wrestling
Versus humans involves light habit-reading
Garry's Mod leans a little harder on variance, though the gap is small.
Garry's Mod
Hidden roles and player chaos in popular modes
The Simpsons Wrestling
Janky collision adds accidental randomness
Garry's Mod leans a little harder on optimization, though the gap is small.
Garry's Mod
Contraption building rewards systems knowledge
The Simpsons Wrestling
Each character's spam-able power move is quickly found
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.