Sub Vergleich()
        Dim i, j, k As Integer
        Dim IDexists, IsDifferent As Boolean
          i = 10
Do Until IsEmpty(Worksheets(1).Cells(i, 1))
 
            IDexists = False
 
            j = 10
            Do Until IsEmpty(Worksheets(2).Cells(i, 1))
                If Worksheets(1).Cells(i, 1) = Worksheets(2).Cells(j, 1) Then
                    IDexists = True
 
                    For k = 2 To 100
                       If Worksheets(1).Cells(i, k) <> Worksheets(2).Cells( _
                         j, k) Then
                            Worksheets(1).Cells(i, k).Interior.ColorIndex = 4
                        End If
                    Next
 
                End If
                j = j + 1
           Loop
 
            If (IDexists = False) Then
              Worksheets(1).Cells(i, 1).Interior.ColorIndex = 4
             End If
 
 
            i = i + 1
 
Loop
 
    End Sub