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
An early arcade climber demanding tight, repeatable jump execution.

Execution · Pure Mechanics
Sequel rhythm game with harder setlists and refined plastic-guitar technique.
Donkey Kong Junior leans Execution (Pure Mechanics); Guitar Hero II leans Execution (Pure Mechanics).
Guitar Hero II leans a little harder on execution, though the gap is small.
Donkey Kong Junior
precise vine-climbing and jump timing
Guitar Hero II
Harder charts, hammer-ons, and three-note chords
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Donkey Kong Junior
enemies follow fixed patrol patterns
Guitar Hero II
Static note highways
Donkey Kong Junior leans a little harder on variance, though the gap is small.
Donkey Kong Junior
minor enemy timing variance
Guitar Hero II
Fully deterministic charts
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Donkey Kong Junior
minimal route memorization needed
Guitar Hero II
Star power pathing for leaderboard play
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.