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 pure loot-and-build treadmill where set-bonus optimisation and Rift pushing define performance.

Optimization · Pure Optimization
A movement-focused looter where build optimisation and endurance meet persistent drop-table variance grinds.
Diablo III leans Optimization (Pure Optimization); Warframe leans Optimization (Pure Optimization).
Warframe leans a little harder on execution, though the gap is small.
Diablo III
Greater Rift pushing has minor mechanical demand in builds
Warframe
Movement and combo timing matter in endgame Steel Path content
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo III
No meaningful adaptive opponent; co-op is cooperative
Warframe
Cooperative PvE only; no adaptive human opponents
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo III
Primal Ancient drops and set dungeon RNG drive the grind
Warframe
Relic cracking and mod drop RNG dominate progression
Diablo III leans a little harder on optimization, though the gap is small.
Diablo III
Set bonuses and paragon levelling are almost entirely solvable
Warframe
Warframe builds and mission routing are extensively community-solved
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.