Datediff with sql server

Date-
1.       select DATEDIFF(MILLISECOND ,GETDATE()-1,GETDATE()) as milisecond


Time-

1.       select right(convert(varchar(30),getdate(),121),12)
                             outpur-- 15:02:24.3424398

2.       SELECT CONVERT(VARCHAR(16), SYSDATETIME(), 14)

                              outpur-- 15:02:24.3424398