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

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Execution · Practiced Mastery
Cinematic third-person shooter campaign of set-piece battles across a dying Cybertron.
Grand Theft Auto V leans Execution (Practiced Mastery); Transformers: Fall of Cybertron leans Execution (Practiced Mastery).
Transformers: Fall of Cybertron leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Transformers: Fall of Cybertron
Third-person gunplay and transform-dodging carry combat
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Transformers: Fall of Cybertron
Multiplayer modes add some human opposition
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Some mission and lobby randomness.
Transformers: Fall of Cybertron
Scripted campaign with minor drop randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Heists, money loops, builds learnable.
Transformers: Fall of Cybertron
Weapon upgrades and loadouts reward light planning
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.