It can be hard to notice where two strings are different in the Apps Script logger. We can borrow JsDiff to help with that.

I’ll be using the cjsDiff library

M9zcCXivXIkjpW_mA_X1Vtiz3TLx7pV4j

You can report on any combination of additions, deletions or no changes. This example does them all.

// compare
  var diffs = cjsDiff.JsDiff.diffChars(
    'quick brown fox jum ove lazy dog', 
    'the quick brown fox jumped over the lazy dog'
  );
  
  
  Logger.log("\n" + diffs.map(function (d) {
    if (!d.removed && !d.added ) {
      return 'no changes--'+d.count + ' chars\n  '+d.value;
    }
    if (d.removed) {
      return 'removed--' + d.count + ' chars\n  '+d.value;
    }
    if (d.added) {
      return 'added--' + d.count + ' chars\n  '+d.value;
    }
	}).join ("\n"));

And the result

added--4 chars
  the 
no changes--19 chars
  quick brown fox jum
added--3 chars
  ped
no changes--4 chars
   ove
added--1 chars
  r
no changes--1 chars
   
added--4 chars
  the 
no changes--8 chars
lazy dog

If that doesn’t quite do it for you, There are various options you can use as documented here

For more like this see Google Apps Scripts Snippets
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