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
WWII team shooter blending aim and squad tactics.

Execution · Grand Arena
Fast arena shooter with deep loadout tuning.
Battlefield V leans Execution (Competitive PvP); Call of Duty: Modern Warfare III leans Execution (Grand Arena).
Call of Duty: Modern Warfare III leans a little harder on execution, though the gap is small.
Battlefield V
Bullet drop and recoil punish sloppy aim
Call of Duty: Modern Warfare III
Fast TTK punishes any aim error
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield V
Flanks and squad play reward map sense
Call of Duty: Modern Warfare III
Sliding and pre-aim duels reward prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield V
Vehicle spawns and chaos create swings
Call of Duty: Modern Warfare III
Spawn flips and map traffic add noise
Call of Duty: Modern Warfare III leans a little harder on optimization, though the gap is small.
Battlefield V
Class loadouts and fortifications optimize holds
Call of Duty: Modern Warfare III
Loadouts, perks, attachments heavily tuned
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.