Let’s look at the typical positions in a soccer team:
The goalkeeper is the only player on a soccer team who is allowed to touch a ball with his hands. He is also the only player to sport a different uniform to the rest of the team. Because of his location, the goalkeeper can see the entire field and has a responsibility to direct his team when he sees moves by the opponents.
The sweeper is the last defender who roams laterally. The job of the sweeper is to watch and anticipate any openings in the defense that he can close. A sweeper does not mark any opposing player. As a result, he can move up to the midfield during an offensive move to defend against a counter-attack.
Fullbacks cover the area along sidelines. When in defense, a fullback covers the attacker or watches the flank for incoming opponents. When the team is mounting an attack, the fullbacks stay wide and sprint up the sidelines to provide support.
The outside midfielder, just like the fullback is expected to be active during offense as well as defense. The winger stays wide during offense and sprints up the sidelines. Staying on the sideline, the winger opens up the game during the buildup to the offensive move. Wingers require great 1v1 skills.
There are several more positions in a typical soccer team. However, these are the ones with some of the key roles during a game.