what is the difference in landing time between a ball dropped vs a ball thrown horizontally from the same height at the same time

The horizontal force and speed have no influence on the vertical force, speed, or acceleration.  This is a fancier way of saying that the behavior of the ball in the vertical direction has no relationship to its behavior in the horizontal direction.  The ball thrown horizontally and the ball dropped vertically hit the ground at the same time.  Same answer for a bullet shot from a gun and a bullet dropped from the gun's muzzle at the same time ...  strange as it may seem.