Why is the Last edited date, displayed in the Help Center article editor, different from the last updated date that is displayed to the end-users in the Help Center?
The reason for the discrepancy between these two dates is as follows:
The Last edited date, returned within the editor, reflects the last time the content of the article was updated.
The Last updated date, outside the editor (shown to end-users), is given by this helper:
The helper reflects the last change to the article's meta-data, which includes new comments and up/down votes (both of which can be done by other end-users). Similarly, if you have localized content, any comment or vote on a translated article will also affect the last updated date shown to end-users for all translations as well as the source article.