Esto te ayudará a comprender las diferencias.
[http://msdn.microsoft.com/en-us/library/ms143531(v=sql.120).aspxfont>[1]
USE master;
SELECT SERVERPROPERTY('BuildClrVersion') AS [BuildClrVersion]
, SERVERPROPERTY('ComputerNamePhysicalNetBIOS') AS ComputerNamePhysicalNetBIOS
, SERVERPROPERTY('ServerName') AS [ServerName]
, SERVERPROPERTY('InstanceName') AS [InstanceName]
, SERVERPROPERTY('Collation') AS [Collation]
, SERVERPROPERTY('ComparisonStyle') AS [ComparisonStyle]
, SERVERPROPERTY('Edition') AS [Edition]
, SERVERPROPERTY('EngineEdition') AS [EngineEdition]
, SERVERPROPERTY('IsClustered') AS [IsClustered]
, SERVERPROPERTY('IsFullTextInstalled') AS [IsFullTextInstalled]
, SERVERPROPERTY('IsIntegratedSecurityOnly') AS [IsIntegratedSecurityOnly]
, SERVERPROPERTY('IsSingleUser') AS [IsSingleUser]
, SERVERPROPERTY('LCID') AS [LCID]
, SERVERPROPERTY('LicenseType') AS [LicenseType]
, SERVERPROPERTY('MachineName') AS [MachineName]
, SERVERPROPERTY('NumLicenses') AS [NumLicenses]
, SERVERPROPERTY('ProcessID') AS [ProcessID]
, SERVERPROPERTY('ProductVersion') AS [ProductVersion]
, SERVERPROPERTY('ProductLevel') AS [ProductLevel]
, SERVERPROPERTY('ResourceLastUpdateDateTime') AS [ResourceLastUpdateDateTime]
, SERVERPROPERTY('ResourceVersion') AS [ResourceVersion]
, SERVERPROPERTY('SqlCharSetName') AS [SqlCharSetName]
, SERVERPROPERTY('SqlSortOrder') AS [SqlSortOrder]
, SERVERPROPERTY('SqlSortOrderName') AS [SqlSortOrderName];
GO
EDITAR:
Nombre de la instancia: El nombre del servidor SQL - INSTANCIA POR DEFECTO, Nombre INSTANCIA (usted da un nombre para la instancia en particular)
ID de instancia: está relacionado con el nombre de instancia. Por ejemplo: cuando presiona Instancia predeterminada, entonces será SQLSERVER el campo generado IDID o su nombre ID de instancia generado.