Well, the simplified physics textbook problem would probably want the
answer "yes," since you can treat Newton's second law and the resulting
kinematics of uniformly accelerated motion separately for the
horizontal and vertical components of the motion. They probably tell
you to treat the air resistance as being zero and treat the Earth as
flat, both of which we know not to be true.
But more realistically, air resistance provides a drag force which
increases with speed and points in the direction opposite to the
velocity of the bullet through the air. The bullet is traveling very
rapidly, mostly horizontally, but with a small downwards component. Air
resistance provides a force that increases nonlinearly with speed, and
so the vertical component of the air resistance force will be greater
for the horizontally shot bullet than for the dropped bullet.
If the bullet is shot very fast, the curvature of the Earth
becomes important (say if this is an artillery shell being shot at a
target many miles away). Shoot a bullet fast enough in the horizontal
direction, ignore air resistance, and you can get it in orbit around
Alternatively, if there's a hill nearby, you could get the opposite answer.
(republished on 07/12/06)