head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Reads · Grand Arena
Cold-War base-builder where tight production queues and superweapon races define competitive play.

Optimization · Grand Arena
Diesel-punk CoH-style RTS with mechs and infantry cover.
Command & Conquer: Red Alert 2 leans Reads (Grand Arena); Iron Harvest leans Optimization (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 2
Superweapon timing and unit grouping require practiced multitasking
Iron Harvest
squad micro and cover
Command & Conquer: Red Alert 2 leans a little harder on reads, though the gap is small.
Command & Conquer: Red Alert 2
Opponent faction and rush timing must be scouted and predicted
Iron Harvest
MP flanks vs humans
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 2
Map layout is fixed; very little hidden RNG in unit behavior
Iron Harvest
fog of war
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert 2
Build queues and power grid management are highly optimizable
Iron Harvest
build orders and unit comps
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.