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
Retro Studios' notoriously tough revival of Donkey Kong Country with relentless set-piece levels.

Execution · Pure Mechanics
Tests twitch run-and-gun execution over memorised one-hit-death enemy patterns.
Donkey Kong Country Returns leans Execution (Pure Mechanics); Super C 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.
Donkey Kong Country Returns
Demanding rocket-barrel and mine-cart sections, strict timing
Super C
One-hit deaths demand precise dodging and aim throughout
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Donkey Kong Country Returns
Scripted hazards, no adaptation
Super C
Enemy waves are fully scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Donkey Kong Country Returns
Hidden puzzle pieces, fixed once found
Super C
Spawns are deterministic once learned
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Donkey Kong Country Returns
KONG letters and time attack routes are learnable
Super C
Memorising spawn patterns and weapon routes solves 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.