1. Horizontal Motion: This is uniform motion, meaning the projectile travels at a constant speed in a straight line. There is no acceleration in the horizontal direction unless air resistance is significant.

2. Vertical Motion: This is uniformly accelerated motion, meaning the projectile experiences a constant acceleration due to gravity. This acceleration acts downwards, causing the projectile's vertical velocity to change over time.

These two motions are independent of each other, meaning they don't affect each other. This is why a projectile follows a curved path - the horizontal motion continues at a constant speed while the vertical motion is affected by gravity.