Question : SERVERPROPERTY('SERVERNAME') & SERVERPROPERTY('MACHINENAME')

Are the above 2 always going to the same, guaranteed?

Are they absorbed at installation of SQL? or do they read from OS, live?

Thanks

Answer : SERVERPROPERTY('SERVERNAME') & SERVERPROPERTY('MACHINENAME')

Nope.  The first will return the instance name while the 2nd returns the physical machine name.