GitHub definitely has more users (4.4m claimed https://github.com/features/community), but I meant the social interaction capabilities and features that GitHub offers.
GitHub is much more organized around community and public feedback (search, stars, comments, etc.), than BitBucket. IMO, neither is claiming to be something they aren't. It just happens that for private repos and hosting where the focus isn't discoverability or community-driven, BitBucket seems like an easy choice. However, if you want to integrate with communities or popular open source groups/code - GitHub is probably a better option.
They're both great overlays for Git, it's just important to keep in mind where their core focus is. For GitHub, community is clearly a front-runner. BitBucket is more focused on private repo options and process management/tools.
I put some sweeping claims in this comment, but there's a lot of really good data in this post to supplement.
I think it helps to think in terms of their revenue model - might help predict what features they develop too:
- bitbucket wants enterprise developers to use it. (so it must be free for the private repos the enterprise needs). It's a gateway drug.
- github wants its offering to be directly valuable to its users (which might be open-source, startup, small, medium or enterprise team).
This predicts that github will be a better as a whole package (including issue tracking etc); and bitbucket will be great for git itself. But there's also much commonality: they both want to attract new users; "viral marketing" (in the sense of social projects pulling more people into the ecosystem) is helpful to both. But I think bitbucket sells itself as "free private repos* so there isn't really an overlap.
I predict that bitbucket must not become a viable alternative to atlassian's paid offerings; but github isn't restricted in that way (of course, they might well add paid offerings).
It seems there's also a danger for bitbucket: if users adopt their issue-tracking etc, it might be painful to upgrade; and so users might as well switch to github or other. Bitbucket should have an auto-upgrade (or, I guess their present issue tracking could evolve into a freemium model... that probably makes the most sense).
Great description, never thought of bitbucket as a gateway drug but absolutely true. Although I don't really get what you mean about issue-tracking. You mean upgrading to Jira?
I would imagine the ease of sharing, searching, following, comments/discussion, pull requests, etc.
I don't have any experience with Bitbucket yet other than making an account and poking around with the interface, so I don't really have a frame of reference, but GitHub does seem to do the above things quite well in my relatively limited experience.
