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

Optimization · Pure Optimization
Balancing town supply chains against mine logistics in a solvable economy.

Optimization · Pure Optimization
The sequel expands the mechanical puzzle boxes into full eerie rooms spanning crypts, ships, and seances.
SteamWorld Build leans Optimization (Pure Optimization); The Room Two leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
SteamWorld Build
Placing buildings has no dexterity component
The Room Two
Slow tactile fiddling, zero dexterity bar
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
SteamWorld Build
Creature attacks are scripted waves, not an adapting mind
The Room Two
No opponent exists
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
SteamWorld Build
Resource layout below ground is unknown until dug
The Room Two
Unknown contraptions until explored, then fixed
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
SteamWorld Build
Supply chains, citizen needs and mine logistics are the entire test
The Room Two
Fixed mechanical puzzles with single deducible solutions
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.