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

Optimization · Pure Optimization
A management game about ferrying spirits to the afterlife.

Optimization · Pure Optimization
Tests creative vocabulary - conjuring the right modified object for each fixed puzzle.
Spiritfarer leans Optimization (Pure Optimization); Super Scribblenauts 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.
Spiritfarer
Platforming is light and forgiving.
Super Scribblenauts
Stylus control matters slightly, never decisively
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Spiritfarer
Spirits follow scripted arcs.
Super Scribblenauts
Solo sandbox - nothing models you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Spiritfarer
Minor resource RNG.
Super Scribblenauts
Puzzles are fixed; your vocabulary is the only variable
Super Scribblenauts leans a little harder on optimization, though the gap is small.
Spiritfarer
Boat layout and crafting loops reward planning.
Super Scribblenauts
Finding object-adjective combos that satisfy each puzzle is the game
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.