If you throw a ball upward while moving in the same direction with the same speed, the ball's overall motion will be a combination of your throwing velocity and the upward velocity imparted to the ball.
Here's what will happen:
The ball will move upward due to the force you applied while throwing it. It will initially rise against gravity.
However, because you and the ball have the same initial velocity in the same direction, the ball will appear to hang momentarily in mid-air relative to you. This is because both you and the ball have the same initial speed, so while you continue to move forward, the ball's vertical motion counteracts your forward motion.
Eventually, gravity will start to slow down the ball's upward velocity, and it will start descending.
As the ball descends, you will continue moving forward, so the ball will fall behind you in the vertical direction.
The ball will eventually reach the ground, while you continue moving forward.
In summary, although you and the ball have the same initial speed and direction, the ball will follow a curved trajectory, rising and falling due to the combination of its upward velocity from your throw and the downward force of gravity.