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 · Practiced Mastery
A grittier crime story where weighty driving and gunplay carry the experience.

Execution · Pure Mechanics
A motion-control party collection testing full-body timing and little else.
Grand Theft Auto IV leans Execution (Practiced Mastery); Kinect Sports: Season Two leans Execution (Pure Mechanics).
Kinect Sports: Season Two leans a little harder on execution, though the gap is small.
Grand Theft Auto IV
Heavier driving and cover shooting reward control.
Kinect Sports: Season Two
Full-body motion timing is the entire skill surface
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto IV
Scripted AI, no adaptive opponent modeling.
Kinect Sports: Season Two
Party opponents barely reward prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto IV
Minor mission variance.
Kinect Sports: Season Two
Sensor reading adds unintended noise
Grand Theft Auto IV leans a little harder on optimization, though the gap is small.
Grand Theft Auto IV
Mission routing and weapon picks learnable.
Kinect Sports: Season Two
Minigames have little system depth to solve
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.