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

Optimization · Pure Optimization
LucasArts adventure sending Indy down three routes toward Atlantis.

Optimization · Pure Optimization
A fixed-solution puzzle adventure where finding the right inventory combination unlocks every obstacle.
Indiana Jones and the Fate of Atlantis leans Optimization (Pure Optimization); The Secret of Monkey Island leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Indiana Jones and the Fate of Atlantis
Pointing and clicking, light fistfight option
The Secret of Monkey Island
Clicking inventory items demands no twitch skill whatsoever
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Indiana Jones and the Fate of Atlantis
No adaptive opposition
The Secret of Monkey Island
No adaptive opponent; all puzzles are fixed and authored
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Indiana Jones and the Fate of Atlantis
Solutions hidden until reasoned out
The Secret of Monkey Island
Some hidden items require exploration but solutions are invariant
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Indiana Jones and the Fate of Atlantis
Three-path puzzle chains reward deduction
The Secret of Monkey Island
Correct item combinations and dialogue chains fully determine progress
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.