<u>Answer:</u>
If we consider vertical velocity both have same vertical velocity of 
Resultant velocity when stone hits the ground is more for thrown horizontally.
<u>Explanation:
</u>
We have equation of motion,
, where u is the initial velocity, u is the final velocity, s is the displacement and a is the acceleration.
When rock is dropped:
Initial velocity = 0 m/s , displacement = H and acceleration = g.

When rock is thrown horizontally:
Considering vertical motion of rock
Vertical initial velocity = 0 m/s ,Vertical displacement = H and vertical acceleration = g.

If we consider vertical velocity both have same vertical velocity of 
But stone thrown horizontally will have horizontal velocity also, so it has more velocity if we compare resultant velocity.