tribble is the beta code
redshirt is a release candidate
holodeck is live.
does that make sense?
edit: I think that;s right. Someone please check me on that.
It is incorrect.
As currently constituted, Tribble is the Season 6 beta server; major game elements to be included in the Season 6 release will be tested on Tribble. Ideally, these elements will undergo several test iterations before S6 goes to Holodeck. (This also means that content updates that go Live will be ported to the Tribble code branch to ensure version compatibility.)
Redshirt is the short-term test server; quick content patches (typically C-store items) that are to be released almost immediately will be put on Redshirt for a cursory "will this make the servers explode?" test run before being pushed to Holodeck. Hopefully, a few days testing will take place, but don't be surprise if the time between Redshirt testing and going Live is counted in hours.
Note that when S6 goes live, it will not be sent to Redshirt at all.