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

Execution · Practiced Mastery
The Genesis Castlevania tours war-torn Europe with whip-wielding John Morris and spear-vaulting Eric Lecarde.

Execution · Pure Mechanics
Spectacle hack-and-slash where reflexes and combo flow drive every fight.
Castlevania: Bloodlines leans Execution (Practiced Mastery); God of War III leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania: Bloodlines
Stiff classic movement against demanding Genesis bosses
God of War III
Combo execution and QTE timing carry combat.
God of War III leans a little harder on reads, though the gap is small.
Castlevania: Bloodlines
Scripted monsters throughout
God of War III
Bosses fully scripted spectacle.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania: Bloodlines
Minor hidden items only
God of War III
Almost no randomness.
Castlevania: Bloodlines leans a little harder on optimization, though the gap is small.
Castlevania: Bloodlines
Character choice changes paths; patterns are learnable
God of War III
Upgrade paths short and obvious.
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.