The difference is the Plex data folder and the registry branch, which both are stored inside the old windows installation.
That is where Plex stores its information about the media files, which library is monitoring which drive and folder etc.pp.
Your best bet would be to
- move the Plex data folder to a place which can be seen and written to from both Windows installations. You better make sure that all drive letters are identical! [HowTo] An extended guide on how to move the Plex data folder on Windows
- make sure that the Windows user account under which you will be running Plex Server has both “read” and “write” privileges to all files, folders, and subfolders of the shared Plex data location. This will be separate in each Windows installation, so you will have to check and grant privileges twice.
- export the “Plex Media Server” branch of the registry from the old Windows installation
HKEY_CURRENT_USER\Software\Plex, Inc.\Plex Media Serverand import it into the new Windows installation
If you do this in the above order, your Plex Server under the new Windows will have the exact same data and libraries as the old Windows.
