Whilst there is clearly some kind of relationship, Passive Solar and Passive House are not synonymous. In fact, if anything the relationship is generational; instead of being siblings, it might be said that Passive Solar and Passive House share a grandfather / grandchild relationship. More here
The concepts of superinsulation, airtight envelopes, energy recovery ventilation, high performance windows, and managing solar gain originated in the United States and Canada decades ago, a reaction to the OPEC oil embargo. In fact, American Nobelist Dr. William Shurcliff wrote in the 1980s about passive houses. For a summary of North America’s pioneering energy history, see Katrin Klingenberg’s blog post on the North American roots of the passive building movement.
Interest in conservation waned in the United States for many years. During that time, the Europeans refined the application of these principles and spawned demand for high-performance products. Dr. Wolfgang Feist, a German physicist, and Dr. Bo Adamson, a Swedish scientist, led the effort to refine the principles and develop the design techniques and the Passivhaus performance metric. The first Passivhaus was built in Darmstadt, Germany. Feist went on to found the Passivhaus Institut (PHI), which is headquartered in Darmstadt.