What is the difference between Subject(s) in the Refine results section and Keywords in the expanded preview of the article?

Zendy contains material from lots of different sources. The Subject facet uses one set of subject terms for all the material in Zendy so that you can find everything related to that subject, no matter where the original publication comes from. In the expanded preview, the Keywords are descriptors that are used by the different source publishers, or may even come from the authors themselves.