How do I find out what exactly changed from one Fresh release to the next?
You just have to go one level up (and find yourself in a not-so-friendly page)
The English notes are the ones without any language reference. Translations are indicated by the last two letters e.g. Neuerungen und Veränderungen in LibreOffice 4.1 - The Document Foundation Wiki are the notes in de = Deutsch = German
If you want the fine details between each third level release (and each RC, Beta, Alpha, etc) you will need to read these
Those are the updated release notes for the major release number (4.2) but I would like to know what changed between 4.2.3 and 4.2.4…
@lonoob, answer edited to include the third level release details
@karolus, bug fixes ARE important changes from a user perspective! Minor releases only means that no features are added
log files with the bug fixes and commits for all releases in: Bug fixes and commits logs