Here's a quick and obviously dirty (also subjective) comparison between the two paradigm.
Based on what Zero Point Software team define on their website, AAA Indie is:
- AAA Indie is AAA games done independently from publishers.
- AAA Indie is the gamer and the developer, no one else.
- AAA Indie is development with open doors, so gamers can track games in development.
- AAA Indie lets the gamers 'vote' for the games they want to play - simply by expressing their interest.
- AAA Indie is open for anyone with a dream a the will to deliver on that dream.
- Opensource is anything but dependent.
- Opensource is the user and the developer.
- Opensource is open (otherwise it would be called Closedsource), so users should be able to keep up with the development progress.
- Opensource lets users express their interest.
- Opensource is -quoting from above- open for anyone with a dream a the will to deliver on that dream.
Furthermore, AAA Indie was somewhat relying on user contributions, i.e. donations. With more users supporting the development, they will eventually form a community. All of these are also traits in typical opensource development. The only difference was that AAA Indie did not explicitly open an opportunity to let other developers join the development team.
Nevertheless, opensource or not, this new trend might be a good thing in the game development. Hopefully new AAA games would be available to many gamers without the need of game publishers meddling in and boost the pricing during the process.