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 playable pop album blending rhythm, racing, and shooting into a forgiving stylish ride.

Execution · Practiced Mastery
A stylish call-and-response rhythm adventure where reporter Ulala dances to save the galaxy.
Sayonara Wild Hearts leans Execution (Practiced Mastery); Space Channel 5: Part 2 leans Execution (Practiced Mastery).
Space Channel 5: Part 2 leans a little harder on execution, though the gap is small.
Sayonara Wild Hearts
Moderate dodging and timing, deliberately forgiving
Space Channel 5: Part 2
Precise timing on call-and-response button sequences
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Sayonara Wild Hearts
Scripted pop-album set pieces
Space Channel 5: Part 2
Sequences are scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Sayonara Wild Hearts
Fixed levels with memorizable layouts
Space Channel 5: Part 2
First playthrough hides upcoming commands
Space Channel 5: Part 2 leans a little harder on optimization, though the gap is small.
Sayonara Wild Hearts
Gold-rank score chasing rewards route learning
Space Channel 5: Part 2
Memorizing every routine for perfect runs
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.