head to head
The Jackbox Party Pack 10 asks more than Garry's Mod, and the gap is reads.

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

Reads · Bluff & Deduction
A party collection of social minigames played via phones with friends.
Garry's Mod leans Reads (Light / Casual); The Jackbox Party Pack 10 leans Reads (Bluff & Deduction).
Garry's Mod leans a little harder on execution, though the gap is small.
Garry's Mod
Varies by mode; base sandbox is undemanding
The Jackbox Party Pack 10
No physical skill, just typing/drawing on phones.
The Jackbox Party Pack 10 leans clearly harder on reads.
Garry's Mod
Social deduction modes like TTT involve humans
The Jackbox Party Pack 10
Outguessing and bluffing other human players drives scoring.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Garry's Mod
Hidden roles and player chaos in popular modes
The Jackbox Party Pack 10
Prompt randomness and voting variance shape outcomes.
Garry's Mod leans a little harder on optimization, though the gap is small.
Garry's Mod
Contraption building rewards systems knowledge
The Jackbox Party Pack 10
Little to master beyond humor and social reading.
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.