head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

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

Execution · Pure Mechanics
Pure jump timing over fully fixed, memorisable levels.
Donkey Kong Country Returns leans Execution (Pure Mechanics); Super Mario Bros. 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 Mario Bros.
Perfect inputs trivialise momentum jumps over fixed hazards
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 Mario Bros.
Goombas walk left forever - nothing to predict
Donkey Kong Country Returns leans a little harder on variance, though the gap is small.
Donkey Kong Country Returns
Hidden puzzle pieces, fixed once found
Super Mario Bros.
Every level is identical on every run
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 Mario Bros.
Level memorisation and warp routing are fully solvable
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.