Comparing columns and highlighting differences

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Avoid using merged cells.
I deleted the first row for that reason.
And applied this macro:

Sub snb()
  sq = Cells(1, 1).CurrentRegion
  sn = Cells(1, 5).CurrentRegion
  For j = 2 To UBound(sq)
    For jj = 2 To UBound(sn)
      If sq(j, 2) = sn(jj, 3) Then
        Cells(jj, 5).Resize(, 5).Interior.ColorIndex = IIf(sq(j, 3) = sn(jj, 4), 12, 10)
        Cells(j, 1).Resize(, 3).Interior.ColorIndex = IIf(sq(j, 3) = sn(jj, 4), 12, 10)
        Exit For
      End If
    Next
  Next
End Sub

an alternative:

Sub tst2()
  On Error Resume Next
  sq = Cells(1, 1).CurrentRegion
  For j = 2 To UBound(sq)
    With Columns(7).Find(sq(j, 2)).Offset
      If Err.Number = 0 Then
        .Offset(, -2).Resize(, 5).Interior.ColorIndex = IIf(.Offset(, 1) = sq(j, 3), 14, 16)
        Cells(j, 1).Resize(, 3).Interior.ColorIndex = IIf(.Offset(, 1) = sq(j, 3), 14, 16)
      End If
      Err.Clear
    End With
  Next
End Sub