I downloaded Xojo for Windows onto a Windows 10 VM and copied my macOS plugins into the Xojo application folder. On launching it showed the plugins being launched, but on running it gave hundreds of compile error that the plugin items (eg SQLDatabaseMBS) could not be found. When I downloaded the Windows-version plugins from the MBS web site, replacing the macOS plugins, the application ran (on Windows) without error.
This is what led me to believe that there must be a difference between macOS, Windows and Linux plugins from MBS.