Continuing the NNFBG (sounds like one of those acronyms you use to tell someone off, no?) I'm taking a look at some common terms used in conjunction with the defensive line.
In the last post it was requested that we talk about "X-technique" when it comes to DL's, so we'll start with that.
The "technique" for a DL refers to where they line up. The numbers correspond with the offensive linemen and the gaps in between them. Essentially you either line up straight over the other player, like nose-to nose, you can line up over one of his shoulders (shaded) or you can line up in the gap.
There are a lot of varying diagrams of this. The jist is that most guys line up over some part of the opposition's body, rarely completely in the gap, but that's a grey area. The pictorial that explains this is after the jump, and I created it based off of others so there wouldn't be any copyright issues. Have a look.
In general, the nose-tackle in a 3-4 will line up over the center, and the 5-tech will line up over the tackle. In Vic Fangio's 1-gap DL scheme (remember yesterday's NNFBG post, 1-gap DL's penetrate the gaps rather than hold their ground) the DL's will pick a gap and "shoot it". Since they line up mostly right over the opposing player, they can go to either side and keep him guessing.
In a 4-3 there would be a 3-tech lined up in the gap between guard and tackle, then the 7-tech lined up outside of the tackle, threatening the edge. Philadelphia often plays a "Wide-Nine" look, where the defensive ends line up outside of the TE, even if there isn't a TE lined-up on that side. The goal there is to make the OT get way out to the edge in a hurry, something many have a hard time doing.
In a 2-gap 3-4 the players would line up mostly in the same place but they would look to stand their ground and make plays in either gap, whichever the ball-carrier comes through.
In general if a guy is a fast penetrator, a good pass-rusher, fast and furious, he'll be a 4-3 player shooting the gaps or rushing the edge. The stronger guys who can handle blocks, sometimes multiple blocks, will be scouted to play in a 3-4. There are always exceptions though.