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

Optimization · Practiced Mastery
Sandbox warfare testing directional combat skill atop an optimisable army and trade economy.

Execution · Practiced Mastery
Plannable stealth routing punctuated by precise ballistic marksmanship.
Mount & Blade leans Optimization (Practiced Mastery); Sniper Elite III leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mount & Blade
Directional blocking and couched-lance timing demand real skill
Sniper Elite III
Ballistic long shots demand steady, compensated aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mount & Blade
AI lords and battle tactics are mappable scripts
Sniper Elite III
Enemy AI follows mappable alert and search routines
Mount & Blade leans a little harder on variance, though the gap is small.
Mount & Blade
World events, prices and tournaments shuffle each campaign
Sniper Elite III
Patrol details and wind vary slightly per attempt
Mount & Blade leans a little harder on optimization, though the gap is small.
Mount & Blade
Army composition, trade economy and fief management drive conquest
Sniper Elite III
Open maps reward planned routes, sound masking and relocation
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.