Question about release, package and upgrade

As Joplin development became hugely active, I began to don’t understand : what the difference between releases and pre-releases (as releases don’t have significant number and don’t, almost visibly, seems to have a stabilized feature base) ? I can’t see my way in all of this.
On another way, I’d like to know the real difference between the mac package and the dmg package on the download platform on Joplin repo on GitHub, just for my knowledge.
And last, but not least, I’d like to know if Joplin could be distributed by Homebrew, that would help to simply maintain versions of a bunch of FOSS softwares ?
Sorry if my questions are misplaced, I didn’t find a best topic to ask…