The difference between parkour and freerunning typically comes down to the types of moves used by the person engaged in the activity and whether there is any form of competition being utilized. Parkour is generally viewed as an acrobatic means of getting from one point to another in the most efficient and direct manner possible. Freerunning is, on the surface, nearly identical to parkour, except additional moves can be added for purely aesthetic flair, such as spins and flips. Parkour and freerunning also typically differ in that parkour is meant to be free from competition, while freerunning can be performed competitively in a way more similar to a sport.
Both parkour and freerunning share the same origin, though they have diverged from each other in certain ways. In general, this form of athletic activity stems from observations of various forms of movement used in French military training, as well as movements used by Vietnamese firefighters. These methods were further developed and refined into modern parkour and freerunning by several individuals, perhaps most notably David Belle and Sébastien Foucan. The clearest divide between parkour and freerunning can be seen in the different styles of Belle and Foucan, as each has become a leading figure in the two different forms.
Belle is generally considered to be the leader of the parkour movement, and his training and vision for parkour involves efficient movement between locations. This means that extra moves, such as flips and spins, have no place in his form of activity, as they are not efficient and involve unnecessary energy and effort. As Foucan, on the other hand, wished to add such moves to his own movements, the split between parkour and freerunning emerged. Freerunning was first used as a way to provide an English name for parkour, but has since come to typically refer to a form of parkour that includes extra movements for visual flair, such as spins and flips.
A competitive aspect to such athletic movements can also serve as a difference between parkour and freerunning. Belle and other leaders in parkour typically wish for parkour to remain free from competition and exist merely as a personal exploration of the world in a way that can be shared and mutually enjoyed. Freerunning, on the other hand, is often utilized for competitive means and may be engaged in more as a traditional sport. Despite these differences, parkour and freerunning are sometimes used synonymously, though this may elicit the ire of some practitioners of these disciplines.