head to head
Neither is simply harder - they are hard in different places. Dracula: Love Kills demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A horror point-and-click hidden-object adventure about stopping a vampire queen.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Dracula: Love Kills leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Dracula: Love Kills
Point-and-click with light hidden-object timing
Portal
Portal placement timing modest.
Dracula: Love Kills leans a little harder on reads, though the gap is small.
Dracula: Love Kills
Solo adventure, scripted characters
Portal
No adversary modeling player.
Dracula: Love Kills leans clearly harder on variance.
Dracula: Love Kills
Puzzles fixed, minimal randomness
Portal
Deterministic chambers; no randomness.
Portal leans clearly harder on optimization.
Dracula: Love Kills
Puzzle and hidden-object solving is the loop
Portal
Pure puzzle-solving optimization.
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.