Qb: He is the person who starts every play and makes the offensive plays.
Guards: The guards protect the QB. Guards are extremely strong and powerful, and they are very important.
Tackles: Tackles are usually the strongest person on the team, who doesn't care how much they get thrown around. They are important and protect the Qb.
Ends: Less strong people basically slow down blitzing linebackers or go out for passes.
Running backs: The running backs do exactly what their name is--- RUN. They also can go out for passes.
Ends: They basically protect from runs, and try to block passes.
Noseguards: These are very tough people who line up right in front of the center (that's why the name is noseguard). They usually blitz, and try to knock down the center so that the QB gets crushed.
Defensive Tackles: Defensive tackles can "make or break" a game! They blitz a lot and they are strong.
Linebackers: They blitz the most, but stay back if they think there is a pass coming. They usually are fast, strong people, who try to run through a hole in the offense and sack the QB.
Ends: They stay back and cover the wide receivers, but they can also try to tackle the running back if they try to run around the end.
Safety: They are the last line of defense for defense. If someone gets past them, it's a guaranteed touchdown. They usually are the fastest person on the team, and are kind of weak, but strong enough to push people out of bounds.