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 · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.

Execution · Competitive PvP
Couch-competitive archery brawler decided by twitch arrows and reading your friends.
Insurgency leans Execution (Competitive PvP); TowerFall Ascension leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Insurgency
One-shot lethality rewards precise aim
TowerFall Ascension
Arrow aim, dodges, and arrow catches are razor-tight
TowerFall Ascension leans a little harder on reads, though the gap is small.
Insurgency
Human squads flank and adapt each round
TowerFall Ascension
Couch PvP is constant mutual prediction and baiting
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Insurgency
No killcam or HUD hides enemy positions
TowerFall Ascension
Random powerup chests and variants spice rounds
Insurgency leans a little harder on optimization, though the gap is small.
Insurgency
Loadout points and objective route knowledge
TowerFall Ascension
Small fixed arenas leave little system to solve
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.