head to head
StarCraft II: Wings of Liberty asks more than Natural Selection 2, and the gap is reads.

Execution · Grand Arena
Asymmetric FPS-RTS hybrid where aliens and marines fight under live human commanders.

Execution · Grand Arena
Real-time strategy where hands, reads, and build optimization all matter at the top.
Natural Selection 2 leans Execution (Grand Arena); StarCraft II: Wings of Liberty leans Execution (Grand Arena).
StarCraft II: Wings of Liberty leans a little harder on execution, though the gap is small.
Natural Selection 2
Skulk movement and marine aim have steep ceilings
StarCraft II: Wings of Liberty
APM, macro, micro-control under pressure
StarCraft II: Wings of Liberty leans clearly harder on reads.
Natural Selection 2
Human commanders mind-game tech and map control
StarCraft II: Wings of Liberty
1v1 ladder vs adaptive humans modeling you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Natural Selection 2
Symmetric maps, little randomness
StarCraft II: Wings of Liberty
map spawns minor; mostly known
StarCraft II: Wings of Liberty leans clearly harder on optimization.
Natural Selection 2
Tech trees, res flow, and lifeform timings
StarCraft II: Wings of Liberty
build orders, economy curves heavily 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.