head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Competitive PvP
Football sim testing execution and opponent reading under a studied tactical meta.

Reads · Competitive PvP
Open-world pirate game with PvPvE ship combat.
FIFA 21 leans Execution (Competitive PvP); Sea of Thieves leans Reads (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA 21
Skill moves and finishing mechanics demand practiced hands
Sea of Thieves
Ship sailing and naval gunnery require hands
Sea of Thieves leans a little harder on reads, though the gap is small.
FIFA 21
Outguessing a human's defensive shape and attacking patterns is central
Sea of Thieves
PvP ship fights are pure mind games
Sea of Thieves leans a little harder on variance, though the gap is small.
FIFA 21
Deflections, finishing RNG and pack luck colour outcomes
Sea of Thieves
Server encounters, weather, loot vary
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
FIFA 21
Meta formations, custom tactics and squad building are studied deeply
Sea of Thieves
Routes, loadouts, ship setups solvable
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.