This is a great question! The difference comes down to how Scorza processes your GPS data.
Most fitness apps are built with runners and cyclists in mind, so they smooth out sharp changes in direction on the assumption you're following a fairly straight or curved path. This reduces the "noise" in the GPS signal but also means some of the distance you actually covered gets "lost".
For Scorza we want to make sure we're calculating distance covered as accurately as possible for a football player so we actually take the raw GPS positions recorded by your watch and measure the actual distance between each point and then add them all up. This means every change of direction you make on the pitch is captured and counts, rather than "smoothed over".
For a football player making sharp cuts, sprints, and direction changes, we think this gives you a much more accurate picture of the ground you've actually covered even if it looks a little different to what Apple Health shows.