There is a huge difference in the way aiming works in Max Payne 3 compared to Grand Theft Auto 5. In Max Payne 3, your reticle doesn't move from where you're aiming so when you're in free-aim and decide to aim down your sights, you'll be pointing your gun at exactly the same spot you were before you decided to zoom in.
This isn't the case for Grand Theft Auto 5, where the reticle moves upwards when you zoom in and causes you to miss the target you were previously aiming at.
The difference between the two aiming systems is depicted in the GIF above.
In addition to the wonky new aiming system in GTA 5, players are unable to switch from which side the camera is on. This was a feature previously available in both Red Dead Redemption and Max Payne 3, which were also Rockstar titles.