I find bureaucracy scales really well.
Other than that, not a whole lot. Large projects have large teams because there's no other way, not because it's more efficient (per developer). You pay a cost as soon as you add a second person to the mix in terms of inefficiency (ie knowledge transfer and communication).
Largest project I worked on had 70 or so develoeprs across 5 different sites. Even a one line change took a day minimum although that was in part due to the fact that the build took 45+ minutes over a network link from Zurich to London and starting the app took another 45 minutes. Check-ins took about 5 minutes per file. I'm not kidding. The London developers could do this in a fraction of the time.
Anyway, what you tend to find is that on large projects you'll have a bunch of team members that you don't interact with all that much. It's more like a loosely affiliated collection of mini projects. I once read that Microsoft development tended to break down projects into teams of 5-7 developers, even for large projects like Microsoft Office.
Part of the difference is also the difference between small and large companies: larger ones tend to have more process, more rules, less flexibility and so on. But that's by no means guaranteed.
It can be good for career development though. In a small company someone has to leave or die before you can get a promotion (or the company has to be growing such that the team expands and you move upwards) whereas in larger dev departments you can move between teams and so on.
Additionally you can sometimes find some really smart people to attach yourself to and learn from. In small companies being so isolated and self-reliant can be conducive to programmers going a bit "strange", sorta like a hermit.