iDiff View highlights the differences between two versions of a text file.
The left pane shows the older file and the right pane shows the more recent version:
On the iPhone the differences are shown in a combined view. iDiff View is a universal app with adaptive layout, supporting side-by-side apps view on the iPad:
Files are chosen from document providers, such as iCloud Drive, Google Drive, OneDrive etc:
iDiff View shows which characters/words and lines have changed, highlighting additions and deletions.