Its general understanding that SQL Server Difference between @@SERVERNAME and SERVERPROPERTY(‘SERVERNAME’) will return same values. But once I got a different values for both

Select @@SERVERNAME
Select SERVERPROPERTY(‘SERVERNAME’)

were returning different name,  I got answer @ BOL as

@@SERVERNAME function and the SERVERNAME property of SERVERPROPERTY function may return strings with similar formats, the information can be different. […]