head to head
Grand Theft Auto V asks more than Assassin's Creed III Remastered, and the gap is reads.

Execution · Practiced Mastery
An open-world action game where traversal mastery and scripted combat counters carry play.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Assassin's Creed III Remastered leans Execution (Practiced Mastery); Grand Theft Auto V 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.
Assassin's Creed III Remastered
combat counters and traversal need precision
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Assassin's Creed III Remastered
scripted enemy AI, no adaptation
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Assassin's Creed III Remastered
minor loot randomness
Grand Theft Auto V
Some mission and lobby randomness.
Assassin's Creed III Remastered leans a little harder on optimization, though the gap is small.
Assassin's Creed III Remastered
skill trees and synchronization routes solvable
Grand Theft Auto V
Heists, money loops, builds 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.