head to head
Neither is simply harder - they are hard in different places. Risk: Global Domination demands more variance; StarCraft II: Wings of Liberty demands more execution.

Optimization · Grand Arena
Territory math and dice management entangled with reading human alliances.

Execution · Grand Arena
Real-time strategy where hands, reads, and build optimization all matter at the top.
Risk: Global Domination leans Optimization (Grand Arena); StarCraft II: Wings of Liberty leans Execution (Grand Arena).
StarCraft II: Wings of Liberty leans clearly harder on execution.
Risk: Global Domination
Clicking territories takes no physical skill
StarCraft II: Wings of Liberty
APM, macro, micro-control under pressure
StarCraft II: Wings of Liberty leans clearly harder on reads.
Risk: Global Domination
Human diplomacy, truces and betrayal timing cannot be solved
StarCraft II: Wings of Liberty
1v1 ladder vs adaptive humans modeling you
Risk: Global Domination leans clearly harder on variance.
Risk: Global Domination
Dice rolls swing battles and mission cards hide information
StarCraft II: Wings of Liberty
map spawns minor; mostly known
StarCraft II: Wings of Liberty leans a little harder on optimization, though the gap is small.
Risk: Global Domination
Continent bonuses, troop math and border control are calculable
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.