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
Arcade car control across loose surfaces, weather and door-to-door packs.

Execution · Pure Mechanics
Party-sized motion-timing contests with learnable per-event techniques.
Dirt 5 leans Execution (Pure Mechanics); Mario & Sonic at the Olympic Winter Games leans Execution (Pure Mechanics).
Dirt 5 leans a little harder on execution, though the gap is small.
Dirt 5
Sliding off-road cars on mixed surfaces is the whole test
Mario & Sonic at the Olympic Winter Games
Motion-timing and button precision decide every event
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dirt 5
Pack racing adds light wheel-to-wheel jockeying
Mario & Sonic at the Olympic Winter Games
Local human rivals add mild prediction in head-to-head events
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dirt 5
Dynamic weather shifts grip unpredictably
Mario & Sonic at the Olympic Winter Games
Events are fixed; minor physics wobble
Dirt 5 leans a little harder on optimization, though the gap is small.
Dirt 5
Car class knowledge and line choice reward study
Mario & Sonic at the Olympic Winter Games
Each event has a learnable optimal technique
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.