I wanted to make this thread a few years ago when I was looking for the same answers. Hopefully someone like LBz can chime in with a little more nuanced explanation, but...
4-3 Over Plus: when I have seen this front used, it's mainly been as a run stopping front. First time I really noticed it was back when the Ravens ran a 4-3 13 years ago, but it's older than that. Back then they used this as well as the Over-Odd front quite a bit.
In simplest terms, the front shifts to the strong side of the offensive formation. It differs from a conventional 4-3 Over front (which is wrong in Madden). In a conventional 4-3 over (stack in Madden) the defensive tackle shifts to the strong-side in a 3-tech while the defensive end sets on the outside shoulder of the TE. In an over plus, the DT is still in a 3-tech, but the defensive end is slid more heads up, and the outside linebacker is placed on the LOS like so.
Now this is where I say, I hope someone like LBz would chime in with the actual assignments, because in real life, I have seen them play out a few ways. In real life football I have seen the strong-side end slant into the tackle, and I've also seen him play more 2-gap type of stuff on that side to set the edge.
This is where I had a hard time figuring things out with this front because there are no gap assignments programmed into Madden defenses, and there is no edge setting, so I tend to shy away from this front except in certain instances like when I know a power-o play is coming or even stretches. It usually shuts these down pretty well, but other runs, like counter weaks, or dive plays can be precarious, mainly because of the way the linebackers are programmed. They don't attack gaps, so they're apt to just stand there and get eaten up by blocks on runs that come straight at them, and with the ice skating of the runners, they're all kinds of cutback lanes to the weak side that wouldn't be there in real life because of gap assignments, so if your linemen don't get off their blocks, you could be in some trouble in Madden.
The 4-3 Odd: Odd typically means that the center is covered. Honestly, I don't really know what they're doing here in Madden with this front because there literally is no difference this front and a regular 3-4 odd front.
Can you tell which is which?
Here is a breakdown of what the Patriots actually run and its nuances.
http://www.grantland.com/story/_/id/...triots-defense
Another thing that bothers me is that this front in the Madden pic replaced the 4-3 Over Odd front in a lot of 4-3 playbooks. This is the front that was in Seattle's playbook in and Tampa in 2012.
Now I know what this front does. This is a classic run stopping front. The old school Chiefs and the Dolphins pioneered this. It kind of functions as a hybrid front, similar to what Belichick is doing. I have no idea why that front was replaced in the 4-3 playbooks with the 4-3 odd front in Madden 13 because I never saw it run by teams like Seattle or Tampa last year.