In the past, KODI was called XBMC and some of the KODI codes come from XBMC2008. Plex a part of KODI which is more user-friendly but is not an open source app. Plex provider have managed strict controls over their products and therefore it is not possible to install Pirated material on Plex.
One of the attractive features of Plex is that users can set up a main server such as your PC or laptop, and share the contents on various devices like Smart Phones, Tablets, Smart TVs and other streaming devices like Roku, Firestick and so forth. However, difficult and demanding customization would be a disadvantage of Plex.