Compare text in two columns and hilight the differences in another column

[raghuram.star]

Can you please help to compare text in two columns and hilight the differences in another column.

Example

Old Text (Col A)	New Text (Col B)	Comparision (Col C)
It was the humans who was sent to Moon first	But later they said it was animals which was sent to Moon First.	But later they said it was animals which (the humans who) was sent to Moon First.
Is it possible to compare the text in multiple lines like this text is in seperate line a cell in excel is free text8 and any one can tye any thing in it	Can it possible to compare the texts in multiple lines. could it be like this text is in seperate line? This is completely new line of text in the cell which has no trace in the old text Each cell in excel is free text9 and any onebody could tye any thing in it.	Can (Is) it possible to compare the texts in multiple lines. could it be like this text is in seperate lines? This is completely new line of text in the cell which has no trace in the old text Each (a) cell in excel is free text9 (text8) and anybody could (any one can) tye any thing in it.

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</tbody>

Please help me.

I have below code by

Const redCIndex As Long = 3
Const blackCIndex As Long = 0

Sub CheckAgainstColumnA()
    Dim oneCell As Range
    With ThisWorkbook.Sheets("Sheet1").Range("A:A"): Rem adjust
        For Each oneCell In Range(.Cells(1, 1), .Cells(.Rows.Count, 1).End(xlUp))
            oneCell.Font.Color = blackCIndex
            oneCell.Offset(0, 1).Font.ColorIndex = blackCIndex
            Call highlightDifference(oneCell, oneCell.Offset(0, 1))
            Call highlightDifference(oneCell.Offset(0, 1), oneCell)
        Next oneCell
    End With
End Sub

Sub highlightDifference(refCell As Range, testCell As Range)
    Dim refString As String, testString As String
    Dim i As Long, startPoint As Long, newPoint As Long
    
    testCell.Font.ColorIndex = redCIndex
    
    refString = refCell.Text
    testString = testCell.Text
    startPoint = 1
    For i = 1 To Len(refString)
        newPoint = InStr(startPoint, testString, Mid(refString, i, 1))
        If newPoint <> 0 Then
            testCell.Characters(newPoint, 1).Font.ColorIndex = blackCIndex
            startPoint = newPoint + 1
        End If
    Next i
End Sub

I am a novice to VBA and I could not edit it for my need.

Please help me...

 

[raghuram.star]

Can the result be in below fashion, instead of having the result in new column as requed in above request?

Old Text (Col A)	New Text (Col B)
It was the humans who was sent to Moon first	But later they said it was animals which was sent to Moon First.
Is it possible to compare the text in multiple lines like this text is in seperate line a cell in excel is free text8 and any one can tye any thing in it This part of text is there in old text cell only. But this text part is there carryforwaded to new text. And again this is not the in new text cell	Can it possible to compare the texts in multiple lines. could it be like this text is in seperate line? This is completely new line of text in the cell which has no trace in the old text Each cell in excel is free text9 and anybody could tye any thing in it. But this text part is there carryforwaded to new text

<tbody>
</tbody>

Thank you