Well, i think Discogs definition of a release is very near of MusicBrainz’s one in practice. But MusicBrainz doesn’t define it as clearly for now.
Important points in Discogs definition is:
1.4.4. Manufacturing variations should not be counted as a unique release. For example; different stampers / matrix numbers for the same edition, manufacturing tolerance based variations in the shades of label paper or ink color, or unintended vinyl coloration caused by variation in vinyl stock, etc., would not constitute a unique release.
And the notion of “same edition” is perhaps what is lacking in this discussion.
So basically, i don’t know if MusicBrainz officially adopted certain Discogs guidelines, but for sure, in practice, many editors did. Perhaps just because it makes sense, and because many MB editors are also Discogs editors (which isn’t my case).
The fact is Discogs is one of the best sources when it comes to list different editions of an album, and often MusicBrainz is usually far behind in number of releases (not that quantity = quality, but when you have only 10 releases over 250+ editions i would say quality isn’t there either).
@reosarevok: time to improve official guidelines about what is a release or not for MusicBrainz ?