Answer:
Social sciences are about studying human life and society, while other (natural) sciences concern non-human phenomena. Both social and natural scientists are "scientific" since they try to develop logical understandings of their subjects that correspond to real-world experience (empirical evidence) and allow prediction of events (usually under specific conditions). Social scientists have been much less successful at attaining this goal than natural scientists. This is likely because humanity and society are much more complicated than nature -- and more difficult to study from the inside.