Open the required file in viewer for which revisions need to be compared.
Next, follow the steps for navigating to File Viewer More Options.
In the 'More Options' menu, select 'Compare File With' option (under 'More Info' category) to compare the file revision open in viewer with its other revisions accessible to you. Click 'Compare File With' and then select the previous revision from the auto-populating list. The files will open in comparison viewer.
Click here to understand how to compare files in the comparison viewer.
Next Article: View Workflow Instances on a File open in Viewer