I think that Yedda's Explore page shows how Yedda is different from a no-order forum. Yedda has organization by topics. It allows you to browse as well as search for both questions and people by topic.
And it helps that the content on Yedda is free. Wikipedia is free too, but has a different purpose. Wikipedia is an encyclopedia; Yedda is a place for people to ask and answer questions for each other.
