To begin, I would like to warn you that this is going to be a somewhat long-winded answer. I am a UU from birth, so I will (in a fit of egotism) consider myself a bit of an expert on that faith, and while I am not well versed in the teachings of Siddartha Gutama, I think I know enough not to make a complete idiot of myself. In some respects, UUism and Buddhism are quite similar: both religions advocate the individual's right (or responsibility) to his/ her search for 'enlightenment', both claim a high proportion of persons both intelligent AND open-minded, and both faiths are essentially different from other sects in the places of their origins. However, the similarity seems not to go much beyond that point. Buddhism, as I understand it, is an extension of Hindu doctrine, one stating that the way to transcend the cycle of reincarnation is to find the path within oneself. UUism (on a whole) holds no such lofty goals: the purpose of the "free and responsible search for truth and meaning" in the Seven Principles of the UUA is without an actual, stated destination. The search is a purpose in and of itself. Another fundamental difference in dogma is that Buddhism's volume of tennants is far greater than Unitarian Universalism's. The words of the Buddha are well recorded and well adhered to. UUism, on the other hand, derives its heritage from the ideas of many men and women, filtered down through the many commitees, sub-commitees, and group discussions for which Unitarians today are so infamous. As a minor digression, the tennants of Buddhism are also more universal (the irony sickens) than those of UUism. There are also differences in place of origin, structure, history and practices, butif one wanted a simple answer, it would be this: UUism is more humanistic and considerably less rigid than Buddhism. Anyone seeking additional information on Unitarian Universalism should go to the UUA's website, http://www.uua.org/.

Well I don't know much about UU, but I can refine on Captain_Bridge's opinion of Buddhism: There are 3 main branches of Buddhism, they all share these main characteristics: - A practical orientation which focuses on improving the quality and experience of being alive here and now (not in some future lifetime -- the whole reincarnation thing is not even taken literally in many sects). - A general consensus on the basic malfunctions that ail human beings. - A set of remedial practices designed to uproot the causes of the malfunctions. There isn't actually much in Captain_Bridge's account of Buddhism that most Buddhists would even recognize, I think.