"No difference" is not useful to show to users; the diff page for moves in particular is probably pretty common. Instead, show something nice by way of meta-data (currently the log is written in hard-coded in the acting user/content lang)?
Version: 1.25-git
Severity: enhancement
See Also: T55299: diff=prev of first revision of a page says "No difference"; should either show diff of full page or no message
"No difference" is correct because a move or protect produce a null revision which points to the same text blob than the previous revision. The summary is in content language as the reason or most of other summarys by users.
(In reply to Umherirrender from comment #1)
"No difference" is correct because a move or protect produce a null revision
I am aware of how MediaWiki works. :-) It's insanely stupid UX, however.
I have checked this. I think the only possible thing now is for the content model change as that's the only thing revisions know about and which one can easily check for difference.
Protection is tied to title, and the title is tied to the article not revision. So I don't think it is possible to know what changed about them between a revision and subsequent one or between a revision and any other we are comparing with in the current diff view.
But maybe T33306: Revisions should store page title at the time that revision was created can one day change that for the title; and that may make it possible or easier to also know the protection status across revisions.