In terms of gameplay, there are 2 ways to shoot:
Hip fire (effective against many enemies/close range): Default camera setting
During this state player bullets have a default behavior including, recoil, range, rate of fire.
Aiming (faraway enemies/ranged): Holding down a designated key binding (most likely right click)
Will cause the camera to zoom in to the crosshair (middle of the screen) during this time some gun stats could be affected, recoil, range, rate of fire.