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
Combined-arms multiplayer shooter famous for map-altering levolution moments and 64-player conquest.

Execution · Practiced Mastery
Artillery aim under wind combined with fort economy planning against human opponents.
Battlefield 4 leans Execution (Competitive PvP); Worms Forts: Under Siege leans Execution (Practiced Mastery).
Battlefield 4 leans a little harder on execution, though the gap is small.
Battlefield 4
Gunplay, vehicle mastery, and movement under fire
Worms Forts: Under Siege
Manual trajectory aiming under wind decides each shot
Battlefield 4 leans a little harder on reads, though the gap is small.
Battlefield 4
Human teams adapt to flanks and levolution chokes
Worms Forts: Under Siege
Human opponents to outguess on building and target priorities
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 4
Map-altering events and spawns inject noise
Worms Forts: Under Siege
Wind, crates and terrain damage randomize turns
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 4
Loadout tuning and objective rotation knowledge
Worms Forts: Under Siege
Fort placement and weapon-tech 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.