head to head
King of the Castle asks more than The Jackbox Party Pack 3, and the gap is reads.

Reads · Pure Mind Games
A social narrative party game of human players scheming for control of a kingdom.

Reads · Bluff & Deduction
The pack with Trivia Murder Party and Fakin' It, built on out-guessing the room.
King of the Castle leans Reads (Pure Mind Games); The Jackbox Party Pack 3 leans Reads (Bluff & Deduction).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
King of the Castle
Voting and chatting, no twitch demand
The Jackbox Party Pack 3
Phones-as-controllers, near-zero dexterity.
King of the Castle leans clearly harder on reads.
King of the Castle
Outmaneuvering many human players' alliances is the core
The Jackbox Party Pack 3
Trivia Murder Party and Fakin' It reward reading the room.
The Jackbox Party Pack 3 leans a little harder on variance, though the gap is small.
King of the Castle
Some random events shift the political landscape
The Jackbox Party Pack 3
Random prompts and question draws.
King of the Castle leans clearly harder on optimization.
King of the Castle
Managing factions and resources underpins the social play
The Jackbox Party Pack 3
Light trivia and betting math.
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.