No, that is not true. In the absence of air resistance, both bullets, when dropped and shot horizontally from the same height, would hit the ground at different times. The bullet shot from the gun would hit the ground first, while the dropped bullet would take longer to reach the ground.
When a bullet is shot from a gun, it acquires a horizontal velocity due to the force generated by the gunpowder explosion. This horizontal velocity allows the bullet to cover a larger horizontal distance in the same amount of time it takes for the dropped bullet to fall vertically. The dropped bullet only experiences vertical acceleration due to gravity.
However, in reality, air resistance plays a significant role, which can affect the motion of the bullets. The bullet shot from the gun may have a different trajectory due to the interaction with air resistance, which can further affect the time it takes to reach the ground. Therefore, it's challenging to precisely predict the exact landing time of both bullets in real-world conditions.