Why query showing different result while changing just select statement (Columns to show)

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SQL

SQL-Server-2008R2

There is a table called 'NetworkSettings'

CREATE TABLE [dbo].[NetworkSettings](
    [MpnMappingId] [bigint] IDENTITY(1,1) NOT NULL,
    [PartNumber] [nvarchar](50) NULL,
    [MPN] [nvarchar](50) NOT NULL,
    [Network] [int] NOT NULL,
    [Description] [nvarchar](500) NULL,
    [System] [nvarchar](100) NULL,
    [Damaged] [nvarchar](50) NULL,
PRIMARY KEY CLUSTERED
(
    [MpnMappingId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

Now, if we execute below two quires:

SELECT Network FROM
  (
   SELECT
    ROW_NUMBER() OVER (PARTITION BY MPN ORDER BY MPN) AS RowNum,
    MpnMappingId, PartNumber, MPN, Network, [Description], [System], Damaged
   FROM
    NetworkSettings
  ) AS t
  WHERE
   t.RowNum = 1

and query below

SELECT * FROM
  (
   SELECT
    ROW_NUMBER() OVER (PARTITION BY MPN ORDER BY MPN) AS RowNum,
    MpnMappingId, PartNumber, MPN, Network, [Description], [System], Damaged
   FROM
    NetworkSettings
  ) AS t
  WHERE
   t.RowNum = 1

Both shows different results in Network column. but no of count are same.

Can any one tell reason for it? Also, in both case how SQL query runs and shows differnt results?