We've done that frequently with the Aurora channel too, so in terms of release management rules, it's just a new name and focus for an existing channel.
Does it mean
Developer Edition == Aurora + different default settings + additional tools?
Or, what are the exact differences between Aurora and Developer Edition?
Yeah, pretty much. "Developer Edition" is the new name for the Aurora channel. There is no more "Aurora."
(Well, almost. The "Developer Edition" stuff is desktop-only for now, so the alpha-branch builds for Android are still branded as "Aurora." But Aurora for Andoid and Dev. Edition for desktop are built from the exact same source code.)
callahad:
"5. We have a new channel, which new rules." (sic)
Note that the Developer Edition is definitely new (1), and callahad also explains in his reply where it is positioned:
"As far as fundamental web platform features are concerned, the Developer Edition is a normal pre-Beta channel. It's primarily that more willing to promote new tooling up from Nightly into the DevEdition or to set different default preferences, for instance."
1) https://hacks.mozilla.org/2014/11/mozilla-introduces-the-fir...