With versioning activated in your project (Project home > Settings > Document versioning), import the target texts as if they were source texts, using Reimport > No (and a search for the other file version) to create a version history. Then select History/Reports... from the context menu of the file in the Project home > Translations list.
Select the "major versions" of interest and export a two-column view of the changes.
This view will be an HTML file.
The columnar comparison of the two versions shows differences highlighted and some statistics on them.