But this is a hobby, and most of the disputed designations being discussed here arose from the various hobbyist communities, not from official factory nomenclature.
Everyone knows that boss. I'd just add that many of the designations collectors use arose from S&W and from factory literature.
Companies, whether they make guns or automobiles, produce them for a profit and with that foremost in mind. They make design changes or name changes as they see fit or as the market or contracts demand. They are not so interested in keeping track of the name changes that they make or the details of the variations. They can't tell ya how many guns were shipped with a combination of new and old features decades after the fact, they did not care for the most part.
The shooters who loved their guns and historians did care and started keeping track. They developed a nomenclature to help keep it sorted out that often builds on factory nomenclature. For good or ill and with some disputes those designations stand. This works for S&W aficionados, Colt collectors, Ruger guys, Luger folks and many others. It also works for Chevy and Dodge guys, the saber-metricians of baseball, stamp collectors, etc., etc.