Adidas designs every World Cup ball, and on top of being a big seller for them, engineers at the company are constantly a little closer to the perfect ball, Goff says. The ideal soccer ball is a pimple-covered, perfect sphere, its surface just subtly textured enough to keep the airflow around the ball slightly turbulent. Unintuitive as this might sound, the ridges and pimples on the ball make it more aerodynamic, helping the ball to fly through the air more stably.
However, in Goff’s wind tests, he and his team noticed that the Telstar 18 had a little more resistance at high speeds, and predict that the ball will go about eight to nine percent less distance down the pitch on long kicks. This means that Manuel Neuer, the goalkeeper for Germany who was considered to be the x-factor that brought Germany the win in 2014, might not have quite as much of an impact clearing balls from the goal this time around Goff says. “You’d see him just kicking the ball way, way down the pitch, and [this World Cup] you might notice that some of those kicks aren’t quite as long as before,” Goff says.
Everything becomes scaled down for smaller soccer players compared to the adult game. Kids play on small fields nowhere near the size of a full regulation field 100 or more yards long, with as few as three players compared to 11 for grownups. Even in a league, parents may serve as referees, games may last only 20 minutes and scores more than likely won't be kept. In keeping with this small world, kids' soccer balls are also smaller.
On the other hand, replicas (sometimes called training balls or gliders) are designed to be just like the official match balls but are much cheaper. Their panels are often stitched rather than thermally-bonded and are made of a different material. However, they’re not necessarily less durable than official match balls. So, they’re the recommended option for most players. https://www.youtube.com/watch?v=j2Xn84L3Kcs