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 castle-building strategy game where economic optimization and defense planning is the whole test.

Optimization · Pure Optimization
Optimising road networks and production chains at a settler's pace.
Stronghold leans Optimization (Pure Optimization); The Settlers II: 10th Anniversary 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.
Stronghold
minimal, mostly clicking and management
The Settlers II: 10th Anniversary
Slow road-laying needs no dexterity at all
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Stronghold
AI opponents are scripted, minor prediction
The Settlers II: 10th Anniversary
AI opponents expand on predictable scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Stronghold
minor resource and raid randomness
The Settlers II: 10th Anniversary
Map resources are scripted-but-unknown until explored
Stronghold leans a little harder on optimization, though the gap is small.
Stronghold
economy and castle-building near-solvable
The Settlers II: 10th Anniversary
Road networks and production chains are the entire 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.