Option Explicit
Sub vergleich()
    Dim Wks1xAchse As Long, Wks2xAchse As Long, xAchse As Long, yAchse As Long
    Dim Wks1yAchse As Long, Wks2yAchse As Long, Zeilen As Long, Spalten As Long
    Dim QuellSuche, ZielSuche As Range
    Wks1xAchse = Worksheets(1).UsedRange.SpecialCells(xlCellTypeLastCell).Column
    Wks1yAchse = Worksheets(1).UsedRange.SpecialCells(xlCellTypeLastCell).Row
    Wks2xAchse = Worksheets(2).UsedRange.SpecialCells(xlCellTypeLastCell).Column
    Wks2yAchse = Worksheets(2).UsedRange.SpecialCells(xlCellTypeLastCell).Row
    If Wks1xAchse > Wks2xAchse Then
        xAchse = Wks1xAchse
    Else
        xAchse = Wks2xAchse
    End If
    If Wks1yAchse > Wks2yAchse Then
        yAchse = Wks1yAchse
    Else
        yAchse = Wks2yAchse
    End If
    ReDim excel1(yAchse, xAchse) As Variant
    ReDim excel2(yAchse, xAchse) As Variant
    Worksheets(2).Select
    excel2() = Range(Cells(1, 1), Cells(yAchse, xAchse))
    Worksheets(1).Select
    excel1() = Range(Cells(1, 1), Cells(yAchse, xAchse))
    For Zeilen = 2 To yAchse
        Set QuellSuche = Worksheets(2).Range("A1:A" & yAchse).Find(excel1(Zeilen, 1), Lookat:=xlWhole)
        Set ZielSuche = Worksheets(1).Range("A1:A" & yAchse).Find(excel2(Zeilen, 1), Lookat:=xlWhole)
        If Not QuellSuche Is Nothing Then
            For Spalten = 2 To xAchse
                If excel1(Zeilen, Spalten) <> "" And excel1(Zeilen, Spalten) <> excel2(QuellSuche.Row, Spalten) Then
                    Worksheets(1).Cells(Zeilen, Spalten).Interior.ColorIndex = 6
                End If
            Next Spalten
        Else
            Worksheets(1).Range(Worksheets(1).Cells(Zeilen, 1), Worksheets(1).Cells(Zeilen, xAchse)).Interior.ColorIndex = 3
        End If
        If Not ZielSuche Is Nothing Then
            For Spalten = 2 To xAchse
                If excel2(Zeilen, Spalten) <> "" And excel2(Zeilen, Spalten) <> excel1(ZielSuche.Row, Spalten) Then
                    Worksheets(2).Cells(Zeilen, Spalten).Interior.ColorIndex = 6
                End If
            Next Spalten
        Else
            Worksheets(2).Range(Worksheets(2).Cells(Zeilen, 1), Worksheets(2).Cells(Zeilen, xAchse)).Interior.ColorIndex = 3
        End If
    Next Zeilen
End Sub