head to head
Dirt 3 asks more than Red Dead Redemption 2, and the gap is execution.

Execution · Practiced Mastery
Precise rally car control over stages that reward memorisation and tuning.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.
Dirt 3 leans Execution (Practiced Mastery); Red Dead Redemption 2 leans Execution (Practiced Mastery).
Dirt 3 leans clearly harder on execution.
Dirt 3
Car control on loose surfaces is a high physical ceiling
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
Red Dead Redemption 2 leans a little harder on reads, though the gap is small.
Dirt 3
Racing the clock or scripted AI, nobody adapts
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dirt 3
Surface conditions and minor physics noise per run
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Dirt 3 leans clearly harder on optimization.
Dirt 3
Stage knowledge and setup tuning reward study
Red Dead Redemption 2
Loadouts and routes solvable but loose.
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.