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.

Execution · Competitive PvP
Tests trajectory aim and turn planning against human targets amid crate luck.

Execution · Competitive PvP
Turn-based artillery duels testing shot judgement, opponent prediction, and weapon economy under wind.
Worms: Ultimate Mayhem leans Execution (Competitive PvP); Worms World Party leans Execution (Competitive PvP).
Worms: Ultimate Mayhem leans a little harder on execution, though the gap is small.
Worms: Ultimate Mayhem
3D grenade arcs and ninja-rope control reward practiced aim
Worms World Party
Precise angle and power judgement on every shot matters
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Worms: Ultimate Mayhem
Predicting a human's target priorities shapes each turn
Worms World Party
Human opponents reposition and bait - predicting them wins games
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Worms: Ultimate Mayhem
Crate drops, wind and terrain chaos swing rounds
Worms World Party
Wind, crate drops and terrain destruction add real chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Worms: Ultimate Mayhem
Weapon economy and positioning are plannable each turn
Worms World Party
Weapon selection, positioning and turn economy reward planning
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.