head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Pure Mechanics
Finger speed and accuracy against fixed note charts of 80s tracks.

Execution · Pure Mechanics
A brutal minimalist platformer where flipping gravity replaces jumping.
Guitar Hero Encore: Rocks the 80s leans Execution (Pure Mechanics); VVVVVV leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero Encore: Rocks the 80s
Hitting note charts at speed is a pure motor ceiling
VVVVVV
Pixel-perfect gravity flips through spike gauntlets
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero Encore: Rocks the 80s
No opponent, just the chart
VVVVVV
No opponent
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero Encore: Rocks the 80s
Charts are fixed and fully memorisable
VVVVVV
Every hazard is fixed and visible
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero Encore: Rocks the 80s
Star power pathing squeezes out extra score
VVVVVV
Routes are short and obvious; execution is everything
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.