For structured data especially, one has other concerns, which largely fall under "usability" – for example, if one is comparing two documents, one generally wishes to know which sections have changed, or if some sections have been moved around – one wishes to understand how the documents differ. For instance "here 'cat' was changed to 'dog', and paragraph 13 was moved to paragraph 14". One may also wish to have robust differences – for example, if two documents A and B differ in paragraph 13, one may wish to be able to apply this patch even if one has changed paragraph 7 of A. An example of this is in diff, which shows which lines changed, and where the context format allows robustness and improves human readability.
