T-SQL Query to find list of Instances Installed on a machine

Here is a T-SQL Query to find the list of instances Installed on a machine.

DECLARE @GetInstances TABLE ( Value nvarchar(100),  InstanceNames nvarchar(100),  Data nvarchar(100)) Insert into @GetInstances EXECUTE xp_regread   @rootkey = 'HKEY_LOCAL_MACHINE',   @key = 'SOFTWARE\Microsoft\Microsoft SQL Server',   @value_name = 'InstalledInstances'   Select InstanceNames from @GetInstances

OR

Create Table #GetInstances ( Value nvarchar(100),  InstanceNames nvarchar(100),  Data nvarchar(100)) Insert into #GetInstances EXECUTE xp_regread   @rootkey = 'HKEY_LOCAL_MACHINE',   @key = 'SOFTWARE\Microsoft\Microsoft SQL Server',   @value_name = 'InstalledInstances'   Select InstanceNames from #GetInstances drop table #GetInstances

Both the queries are almost similar, except for that first query uses a table variable and the second one uses temporary table.