(This is a slightly edited version of a post from 2010. I don't quite believe in this, but suspect there is a grain of truth in it)
The difference between Orkut(as it was)and FB is that they belong to two slightly different times, or rather slightly different stages of human society.
Human society started out with tribes, where members were part of an almost organic whole. The more societies have progressed, the more ‘abstract’ they have become – with less and less direct human interactions. Ethically, the move has been from collectivism from individualism.
FB is the social networking site for a society further along the line of progress. Members of such a society are more likely to turn to a social networking site to look for a quick feeling of human warmth, quick social recognition. They will feel the need to talk about themselves, and they will need people to listen. They may be less interested in the opposite. These are services FB is tailored for.
In a society where people are not so lonely however, these desires will be less important. If you’re meeting your social network friends in real life often enough, you’re less likely to seek their attention online. However, if it’s a sufficiently abstract society, this won’t fulfill one’s need for human interactions. In social networking sites, the focus then will be on making more and more new friends. Something that requires more time than the more advanced (Facebook) society won’t have. Orkut is better than FB for meeting new people and making friends and caters exactly to the needs of the society. Further, people in this society are likelier to care less about privacy issues than people in more abstract, individual-oriented societies.
(Photo: This is a cropped version of a photo titled 'Alone in the City' by Flickr user nataliej)