Then I want at least make a suggestion.
Process starts
Differences between books_Calculating differences, please wait ...
Normal case
Differences between books (Results, with existing differences)
Rare case (not unnormal)
Differences between books / No changes found
I think that's certainly doable, right?
Now a further extension
It would be appropriate, if that
Result window (Differences between books) would indicate the names of the compared books or whatever (e.g. in an upper bar).
Easy to get lost in there.