GETUTCDATE()-2 vs DATEADD(d,-2,GETUTCDATE())
There's no real difference there, but when you start using DATETIME2 values, or functions that return DATETIME2 values, you'll get errors.

SELECT SYSDATETIME() - 1 AS [Incompatible]



  Msg 206, Level 16, State 2, Line 17 Operand type clash: datetime2 is
  incompatible with int


For these, you have to use date math functions. 

SELECT DATEADD(DAY, -1, SYSDATETIME()) AS [Compatible]


Aaron Bertrand speaks about this issue briefly in his Bad Habits to Kick series.