head to head
Neither is simply harder - they are hard in different places. LSD: The Game demands more variance; The Last Guardian demands more optimization.

Variance · Pure Chaos
A surreal dream-diary exploration game with ever-shifting abstract environments.

Optimization · Systems & Chaos
Puzzle adventure about coaxing a giant half-tame creature through ancient ruins.
LSD: The Game leans Variance (Pure Chaos); The Last Guardian leans Optimization (Systems & Chaos).
The Last Guardian leans a little harder on execution, though the gap is small.
LSD: The Game
minimal walking input, surreal exploration
The Last Guardian
Slow climbing and platforming, very forgiving
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
LSD: The Game
no opponent, dream-logic environment
The Last Guardian
Trico is willful but not modeling you adversarially
LSD: The Game leans clearly harder on variance.
LSD: The Game
procedurally shifting surreal dream content
The Last Guardian
Trico's unpredictable compliance adds noise
The Last Guardian leans clearly harder on optimization.
LSD: The Game
almost no solvable systems, pure experience
The Last Guardian
Environmental puzzles with intended solutions
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.