Good question...there's not really an easy answer. I can give a little context on how it works though. NCAA and Madden are built off of a shared codebase, and they share all of our major 'engines' (read my latest blog if you want more info on what our engines are). We differentiate in many of the obvious places like penalties and game rules and hash marks and stuff, but typically if you make a change in one game, it shows up in both.
What we have been able to do lately though is start separating tuning variables in a lot of our AI modules - and putting them into a tool that allows us to a.) tune them live (no re-boot, no re-compile) and b.) tune them differently for each game. So for example we can now tune things like:
- How much a player's speed rating translates into 'game speed'
- How the ratings determine the outcome of a tackle
- How the ratings determine the outcome of a block
- How much each 'event' fatigues a player
- etc
And all of these can be different between Madden and NCAA. We have a ton of these...but we keep adding more and more each year since it just makes it so much more sense for the designers to tune the game by themselves without requiring engineering time.
Along with this, we can also 'branch' animation projects and make two different versions of animation sets for each game. We started to do this much more last year with things like tackles (i.e. they both share sets in Hit Stick tackles or Strip Ball tackles, but every other tackle is unique for Madden or NCAA).
So as to your original question, we try to make sure that both games are equally tuned to perfection, but in their own separate way. We may share every line of code and animation in an area like blocking, but if the NCAA designers want to tune their game so you have a long time in the pocket, that's up to them. We typically will share ALL the low-level AI improvements and major/minor gameplay tweaks...but we still also want unique feature sets (so the games don't feel identical). Also there have been quite a few times this year where a feature had been planned to be in both games but either Jeff Luhr (NCAA lead designer) or myself didn't want it in our respective game so it ends up being a 1-game feature.
As for the post from jfsolo about Madden getting features that were 'held out' of NCAA, that has happened, but most times that's actually not how we approach it. It's that NCAA finishes early and we don't have time to get it in there and polish it (the 'breaking out of tackles' feature in Madden 09 is a good example of this).
P.S. I am fiercely competitive...I personally want to dominate NCAA this year. So if you guys want any NCAA improvements, you're going to have to ask somewhere else.