Why is there a distinction made between "OS X" and "Mac OS X"?

Discussion created by 6828935 on Jan 25, 2016
Latest reply on Jan 26, 2016 by AJ Acevedo
All but three of our Mac endpoints report as "OS X". We have three that report as "Mac OS X". 

It's a minor annoyance, but I would like to know how to consolidate them into just one category of OS.