head to head
Rainbow Six Siege asks more than Command & Conquer: Red Alert 2, and the gap is reads.

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

Reads · Grand Arena
A tactical breach-and-defend shooter driven by mind games over angles and gadgets.
Command & Conquer: Red Alert 2 leans Reads (Grand Arena); Rainbow Six Siege leans Reads (Grand Arena).
Rainbow Six Siege leans a little harder on execution, though the gap is small.
Command & Conquer: Red Alert 2
Superweapon timing and unit grouping require practiced multitasking
Rainbow Six Siege
Crisp aim required but TTK is unforgiving.
Rainbow Six Siege leans clearly harder on reads.
Command & Conquer: Red Alert 2
Opponent faction and rush timing must be scouted and predicted
Rainbow Six Siege
Defenders adapt holds; attackers fake and bait.
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
Rainbow Six Siege
Site rotations only; loadouts deterministic.
Command & Conquer: Red Alert 2 leans a little harder on optimization, though the gap is small.
Command & Conquer: Red Alert 2
Build queues and power grid management are highly optimizable
Rainbow Six Siege
Operator picks, gadget placement, and utility usage.
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.