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
Bite-sized item-combination puzzles wrapped in comedy occult cases.

Optimization · Pure Optimization
Lateral-thinking puzzle solving that converges to a walkthrough once solutions are known.
The Darkside Detective leans Optimization (Pure Optimization); The Secret of Monkey Island: Special Edition 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.
The Darkside Detective
Pointing and clicking has no physical bar
The Secret of Monkey Island: Special Edition
Pointing and clicking has no physical ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
The Darkside Detective
Cases are authored scripts, not adapting minds
The Secret of Monkey Island: Special Edition
Insult swordfighting is scripted dialogue lookup, not prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
The Darkside Detective
Solutions are hidden information until items are found
The Secret of Monkey Island: Special Edition
Puzzle solutions are hidden information until discovered
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
The Darkside Detective
Item-combination puzzles each have one fixed answer
The Secret of Monkey Island: Special Edition
Once solutions are known the game is fully solved
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.