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.

Optimization · Pure Optimization
A base-layout and attack-planning puzzle against static player defenses.

Optimization · Pure Optimization
A charming JRPG carried by familiar evolution and party-build routing.
Boom Beach leans Optimization (Pure Optimization); Ni no Kuni: Wrath of the White Witch leans Optimization (Pure Optimization).
Ni no Kuni: Wrath of the White Witch leans a little harder on execution, though the gap is small.
Boom Beach
Tapping troop deployments takes no dexterity
Ni no Kuni: Wrath of the White Witch
Hybrid action-turn combat, low input demand
Boom Beach leans a little harder on reads, though the gap is small.
Boom Beach
Attacks hit static bases - defenders aren't present to adapt
Ni no Kuni: Wrath of the White Witch
Scripted enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Boom Beach
Scouting reveals most info; matchmaking adds some spread
Ni no Kuni: Wrath of the White Witch
Familiar catch and drop rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Boom Beach
Base layouts, troop compositions and timing are the solvable core
Ni no Kuni: Wrath of the White Witch
Familiar evolution and party routing rewarded
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.