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
Optimizing game development decisions around hidden genre-topic match formulas to maximize review scores and revenue.

Optimization · Pure Optimization
Lane defense classic about managing a sun economy against shambling waves.
Game Dev Tycoon leans Optimization (Pure Optimization); Plants vs. Zombies 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.
Game Dev Tycoon
All choices are menu clicks with no physical ceiling
Plants vs. Zombies
Clicking to plant, minimal pressure
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Game Dev Tycoon
No adaptive human competitor to model
Plants vs. Zombies
Zombie waves follow set compositions
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Game Dev Tycoon
Review scores and trend timing have meaningful randomness
Plants vs. Zombies
Wave timing and lane pressure vary mildly
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Game Dev Tycoon
Genre-topic-audience matching and R&D investment are learnable formulas
Plants vs. Zombies
Sun economy and lane setups are near-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.