Working in teams will naturally foster differences of opinion—and that's a good thing. Diverse opinions help ensure all ideas are discussed, problem areas are identified, and the focus of the task at hand is in the right place.
However, things are a little different in the open source world. Open source contributors are passionate—they often give things their all and as such usually have their personalities ingrained in what the do. This happens in the outside world too, but there's a tendency for contributors to be more passionate about something they're doing in their hard-earned free time.