Joffrey If we are only talking about the act of an object falling as the result of gravity, then the two expressions are similar. However, there is a difference in the way we use the two terms. The verb 'fall' simply means to go from one height to a lower height, and the lowest height to which the object falls is usually stated: - The bird fell to the ground. - The worker fell from the second floor to the first floor. - The stock market fell to its lowest point in the last year. - I was running, then I tripped and fell to the ground. - The unmanned ladder tipped too far, fell, and struck the worker on the ground. The phrasal verb 'fall down' does not need to state the lowest height or point of landing because the point at which the falling stopped is usually implied/understood/known: - The bird fell down from the sky. (we assume it fell to the ground) - The worker, who was on the second floor, fell down one flight (one floor). - When he bumped into me, I fell down. (we assume he fell to the ground or the floor) - I was running, then I tripped and fell down. (we assume I fell to the surface that I was running on) - The unmanned ladder tipped too far, fell down, and injured a worker. (we understand that the worker was at ground level)