head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

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

Execution · Competitive PvP
A hero battle royale where teamwork and aim against human opponents decides fights.
Battlefield 4 leans Execution (Competitive PvP); My Hero Ultra Rumble leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 4
Gunplay, vehicle mastery, and movement under fire
My Hero Ultra Rumble
aim and combo timing in battles
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 4
Human teams adapt to flanks and levolution chokes
My Hero Ultra Rumble
predicting human opponent tactics
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
My Hero Ultra Rumble
item and loot drops are random
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
My Hero Ultra Rumble
team comps and loadouts 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.