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.

Execution · Practiced Mastery
A kart racer testing driving precision and item management on user-created tracks.

Execution · Twitch Chaos
Kart racing execution moderated by item randomness and learnable track routes.
ModNation Racers: Road Trip leans Execution (Practiced Mastery); Sonic & All-Stars Racing Transformed leans Execution (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
ModNation Racers: Road Trip
Drifting and boosting at speed demands driving precision
Sonic & All-Stars Racing Transformed
Drift timing and transforming vehicle control reward practice
ModNation Racers: Road Trip leans a little harder on reads, though the gap is small.
ModNation Racers: Road Trip
Versus humans, anticipating weapon use matters somewhat
Sonic & All-Stars Racing Transformed
Human racers add light positional mind games
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
ModNation Racers: Road Trip
Item pickups and weapon spread add kart-racer chaos
Sonic & All-Stars Racing Transformed
Item rolls regularly upend race positions
ModNation Racers: Road Trip leans a little harder on optimization, though the gap is small.
ModNation Racers: Road Trip
Track lines, boost management and shortcuts reward planning
Sonic & All-Stars Racing Transformed
Track shortcuts and drift-boost routes are learnable
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.