You heathens who are going to be left behind tomorrow when the godly are swept up into the skies, if Harold Camping has anything to say about it, will want to straighten out your terminology about the event.
Apocalypse, from the Greek for “unveiling” or “revelation,” is the umbrella term covering the whole process of Christ being revealed as the world comes to the end of time.
Eschaton is the final series of events in history, the end of the world.
Millennium is a period of a thousand years, and Christian millennialists hold that there will be a golden age of a thousand years of Christ’s rule over the earth until the end of history arrives and the universal resurrection takes place and the Last Judgment is carried out.
The Rapture is not the end of the world, oh no, not by a long shot. Dispensational pre-millennialists believe that a select group will have a dispensation sparing them from the tribulation that will precede the millennium. Those are the people expecting to be carried away before the rest of us endure appalling hardships and suffering. All for the best, though, because it comes out right at the end.
So one apocalyptic sequence goes like this (there are other interpretations of the sequence, St. John not being distinguished for clarity in the Book of Revelation): Rapture, Tribulation, Millennium, Eschaton, Last Judgment. Got it?