Private Sub Form_Load()
  Dim S1$, S2$
  S1 = "PC1 , PC2"
  S2 = "PC1 , PC3"
  MsgBox "Neu: " & StrDiff(S1, S2) & vbCr & "Entfernt: " & StrDiff(S2, S1), _
    vbInformation
End Sub
 
Public Function StrDiff$(S1$, S2$)
  Dim i&, Lst$(), V$
  Lst = Split(S2, ",")
  For i = 0 To UBound(Lst)
    If InStr(1, S1, Trim$(Lst(i)), vbTextCompare) = 0 Then V = V & Trim$(Lst( _
      i)) & ", "
  Next i
  StrDiff = Left$(V, Len(V) - 2)
End Function

Gruss,

Zardoz