What’s the difference between a DT, NT, and NG? I know DT are used in 4-3, but otherwise the distinction seems useless.
All three are DT’s (Defensive Tackles)
Nose Tackle and Nose Guard are the same things. You generally hear the term Nose Tackle in a 3-4 defense for the interior of the three defensive tackles.
It is becoming more rare to hear either term NT or NG as they are more often just refered to as DT.
I think you are right in that the distinction is pretty meaningless. There is some distiction for the offensive line and their blocing schemes, but for most all purposes is safe to call them DT’s.
There are two basic defensive formations in football: the 4-3, and the 3-4.
The old, traditional 4-3 has four defenders on the line of scrimmage, with three linebackers behind them. The two outside men are Defensive Ends, and the two interior linemen are Defensive Tackles (DT). In general, the Defensive Ends have been a little smaller and a little quicker, and have been pass rushers. The interior linemen are generally bigger and slower, and their main job is to stuff running backs at the line (Tony Siragusa and Jerry Ball come to mind).
During the 70s and 80s, the 3-4 defense became more popular. In this scheme, you only have 3 defenders on the line of scrimmage, and 4 linebackers behind them. The two outside linemen were still called defensive ends, and the lineman in the middle was called the Nose Guard or the Nose Tackle. The virtue of the 3-4 was its flexibility and versatility. It gave much more responsibility to the linebackers, who were required to be very quick and very versatile.
In the 70s and 80s, the two types of defenses were very different, and that often led to debates and confusion when it was time to pick All-Pro team (how do you pick the “best” defensive tackle when a nose tackle’s job was quite different from a traditional tackle’s job?). Today, the subject is almost moot. You don’t see strict 3-4 defenses much any more, so the terms are becoming less important.
That’s not to say defenses have reverted to the “old” ways. Though most teams now DO line up in a basic 4-3 formation,
NFL defenses today are very complicated, and they show the offenses many different looks.
Nose Guard & Nose Tackle are the same position, just like the Half Back, Tail Back, & Running Back.
Not quite. A nose guard lines up directly over the center, and a nose tackle lines up in one of the gaps to the left or right of the ball.
Occasionally you will still see a NG in lower levels of football (high school or below) where teams employ a 5-2 (5 down linemen and 2 linebackers), but never in college or the pros (well almost never, Nebraska used a 5-2 in the 2001 season when they were getting run all over on by Colorado).
As previous posters have pointed out, the difference between a NT and a DT in a 3-4 or a 4-3 is negligable. Sometimes the lone DT in a 3-4 (not so often used, only 3 or 4 teams in the NFL run one) will be referred to as a NT, but the difference is in the spectator, not the position.