head to head
Grand Theft Auto V asks more than Brothers: A Tale of Two Sons, and the gap is execution.

Optimization · Practiced Mastery
A wordless fairy-tale adventure controlled with one stick per brother.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Brothers: A Tale of Two Sons leans Optimization (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Grand Theft Auto V leans clearly harder on execution.
Brothers: A Tale of Two Sons
Controlling two brothers on one pad takes coordination
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Brothers: A Tale of Two Sons
No opponent
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Grand Theft Auto V leans clearly harder on variance.
Brothers: A Tale of Two Sons
Fully scripted journey
Grand Theft Auto V
Some mission and lobby randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Brothers: A Tale of Two Sons
Light environmental puzzles with single solutions
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.