head to head
Neither is simply harder - they are hard in different places. FIFA 21 demands more execution; Secret Neighbor demands more variance.

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

Reads · Bluff & Deduction
Kids loot a house for basement keys while one of them is secretly the Neighbor in disguise.
FIFA 21 leans Execution (Competitive PvP); Secret Neighbor leans Reads (Bluff & Deduction).
FIFA 21 leans clearly harder on execution.
FIFA 21
Skill moves and finishing mechanics demand practiced hands
Secret Neighbor
Chases, juking, and grabs need real motor skill.
Secret Neighbor leans a little harder on reads, though the gap is small.
FIFA 21
Outguessing a human's defensive shape and attacking patterns is central
Secret Neighbor
The disguised Neighbor wins by out-modeling suspicious kids.
Secret Neighbor leans clearly harder on variance.
FIFA 21
Deflections, finishing RNG and pack luck colour outcomes
Secret Neighbor
Hidden Neighbor identity and random key spawns obscure information.
FIFA 21 leans a little harder on optimization, though the gap is small.
FIFA 21
Meta formations, custom tactics and squad building are studied deeply
Secret Neighbor
House layouts and key routes are mappable with play.
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.