DEFENSIVE END (DE):
A defensive player who lines up at either end of the defensive line. The job of the defensive end is to contain the running back on running plays to the outside, and rush the quarterback on
DEFENSIVE TACKLE (DT):
A defensive player who lines up on the interior of the defensive line. The duties of a defensive tackle include stopping the running back on running plays, getting pressure up the middle on passing plays, and occupying blockers so the linebackers can roam free.
NOSE TACKLE (NT):
The defensive player who lines up directly across from the center. Also known as the nose guard, the primary responsibilities of the nose tackle are to stop the run and occupy the offensive lineman to keep them from blocking the linebackers.
LINEBACKER (LB) :
A defensive player who lines up behind the defensive linemen and in front of the defensive backfield, linebackers are in charge of defending against the run and pass plays. The linebackers are a team’s second line of defense. Each team has two outside linebackers. In a 4–3 defense, teams have one inside linebacker, usually referred to as a middle linebacker. In a 3–4 defense, teams have two inside linebackers.
A defensive back who generally lines up on the outside of the formation and is usually assigned to cover a wide receiver.
A defensive back who lines up in the secondary between, but generally deeper than the cornerbacks. His primary duties include helping the cornerbacks in pass coverage and supporting the run defense.