If a baritone saxophone player plays too loudly and over plays the ensemble through the entire performance, one judge might think that is one error, the bari sax overbalancing. Another judge will feel like that is an error every time the bari sax plays. The judge who calls it one error and feels everything else is good gives the performance a first division. The judge who feels that the balance is a consistent issue and never gets corrected gives the performance a three. That is how those splits happen.