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

Execution · Pure Mechanics
Throttle and counter-steer precision on loose surfaces against the clock.

Execution · Pure Mechanics
Arcade car control across loose surfaces, weather and door-to-door packs.
Colin McRae: Dirt leans Execution (Pure Mechanics); Dirt 5 leans Execution (Pure Mechanics).
Colin McRae: Dirt leans a little harder on execution, though the gap is small.
Colin McRae: Dirt
Car control on loose surfaces is the entire test
Dirt 5
Sliding off-road cars on mixed surfaces is the whole test
Dirt 5 leans a little harder on reads, though the gap is small.
Colin McRae: Dirt
Racing the clock or AI lines, nothing adapts
Dirt 5
Pack racing adds light wheel-to-wheel jockeying
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt
Surface grip and damage add mild run noise
Dirt 5
Dynamic weather shifts grip unpredictably
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt
Setup tuning and corner-line knowledge underpin pace
Dirt 5
Car class knowledge and line choice reward study
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.