head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Plannable stealth routing punctuated by precise ballistic marksmanship.

Execution · Practiced Mastery
Learning scripted mission layouts and executing aim and stealth under pressure.
Sniper Elite III leans Execution (Practiced Mastery); Syphon Filter 3 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.
Sniper Elite III
Ballistic long shots demand steady, compensated aim
Syphon Filter 3
Aim, taser timing and stealth movement carry encounters
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Sniper Elite III
Enemy AI follows mappable alert and search routines
Syphon Filter 3
Enemies run fixed scripts, never model the player
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Sniper Elite III
Patrol details and wind vary slightly per attempt
Syphon Filter 3
Enemy placements are scripted-but-unknown on first runs
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Sniper Elite III
Open maps reward planned routes, sound masking and relocation
Syphon Filter 3
Routes, gadget use and mission layouts are fully learnable
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.