The key ways in which open space conferences differ from regular conferences are:
Some argue that the open space conference is nothing but a new name for a professional workshop and some imposition of rules to keep it flexible, e.g. as in software engineering and the rise of the agile process. Others think it is much more and cite research on consensus decision making and collective intelligence and even on improv theater, indicating that breaking up groups that come together or otherwise "block" group actions with pre-existing agreements are the major problem in all meetings, and constitute more groupthink, to be eliminated by any and all means possible.
Of course, this observation is quite old, and is one of the main reasons that professionals have workshops and conferences. In any multi-track conference or even in a single-track conference where participants skip sessions, by definition not every participant has been exposed to the same information or opinions. As noted above, this is considered particularly desirable for pairs or groups of people who agree strongly to disagree with the majority, as there is a chance that exposing them to different information requires them to discuss it and to perhaps discover areas where they agree with the majority and not each other. This may be considered undesirable by the participants in the short-term, and more desirable in the long-term, e.g. a doctor or scientist strongly opposing a view might discover that he actually agrees with it, and cease to support politicians who also oppose the view - more likely at a conference of doctors with no politicians, and (supporters of the open space conference suggest) even more likely if doctors who block the consensus are forced to separate.
The question of whether to value pre-existing agreements or new ideas more is of course one that cannot easily be separated from general debates on ethics or politics, nor from preconceptions about the subject matter itself, and its impact on real life. It seems likely that open space ideas will continue to proliferate, as open source software ideas did, in response to perceived bias or drawbacks of the original free software idea.
See also: Open Space Meeting, meeting system, agile process, groupthink