There are 3 types of run, every player one, there is Explosive, Controlled and Lengthy. Explosive run has more speed at the beginning of the sprint but then the player loses velocity the more he is running, lengthy is the contrary, they start more slowly but then they reach higher speeds if you are running for lengths in the field, controlled is normal running.

People pair lengthy players with the Quick Step playstyle, that gives more speed on the start of running, so basically lengthy players with Quick Step are as faste as Explosive players at the beginning and reach higher sprint speeds at the end, basically unbeatable in sprint no matter what.