Hi.  No. It's a vba code.  Here's what you do.
From the worksheet, do Alt+F11.  This brings up the vba editor.
From the editor, do "Insert - Module" from the Main Menu.
Paste the code here.

Function CountUnique(s1 As String, s2 As String) As Double
 Dim V1 As Variant
 Dim V2 As Variant
...etc
 CountUnique = N
End Function

Now, back on your worksheet, enter the following into a cell:

=CountUnique(A1,B1)

Make sure A1 & B1 have strings similar to your example (ie "1,2,3,4")
Don't hesitate to post back if you have questions, especially if it's your
first macro.
Again, this was a quick example to get you going.

Tom G wrote...
...

...

It could, but there comes a point at which spreadsheets and procedural
programming languages simply aren't the best tools for the task. Your
task is equivalent to generating generalized crossproducts and counting
up the tuples in which all entries are distinct values. There are other
software packages that'd be much better at this.

However, if you must do this in Excel, you could try the following udf.

Function foo(ParamArray a() As Variant) As Long
 Dim i As Long, j As Long, k As Long
 Dim b As Variant, c As Variant, d As Variant
 Dim x As Variant, y As Variant

 For Each x In a
   If Not IsArray(x) Then x = Array(x)

   For Each y In x

     If IsEmpty(b) Then
       b = Split(y, ",")

     Else
       c = Split(y, ",")
       ReDim d(0 To (UBound(b) + 1) * (UBound(c) + 1) - 1)
       k = -1

       For i = 0 To UBound(b)

         For j = 0 To UBound(c)

           If InStr(1, "," & b(i) & ",", "," & c(j) & ",") = 0 Then
             k = k + 1
             d(k) = b(i) & "," & c(j)
           End If

         Next j

       Next i

       ReDim Preserve d(0 To k)
       b = d
       Erase c
       Erase d

     End If

   Next y

 Next x

 foo = UBound(b) + 1

End Function