The Color Wheel of the Apocalypse
Postmillenialism: The belief that things will get better and better, until the kingdom of earth reaches a moral tipping point, triggering the return of Christ. Also called the stairway to heaven. Very popular in Victorian times, but not so much now. The 'post' implication in the title indicates that we're living the millenium now, and the actual reign of Christ will involve a recreation of this earth in the perfect image of God.
Premillenialism: The basic selling point of the premil movement is that the book of the revelation is a literal transcription of what's going to happen at the end of the world. The only argument is the exact order of events. Do the elect get pulled before the tribulation, or after. Is there one last crusade of christ, one last opportunity for redemption following the tribulation, or is just a warm up for the inevitable lake of fire. This is the predominant view of most christians, as romaticized by the whole Left Behind series. It's one of those things that if you sit down with a christian press them, they should be embarassed about. I mean, seriously folks.
Amillienialism: I'm not sure how best to express this belief system. Well, the basic point is that the book of the revelation is mostly fiction. Hyperbole. The thousand year reign of christ is now, it's not a literal period of time. There are fractured opinions about the actual end of time. This whole 'return of christ' thing is a bit iffy, with some folks believing that the rapture is death, the millenium is christ in our lives, and judgement day is the individual reckoning between the sinner and the saint. Life is the tribulation. Anyway. Oh, and one extension of amillenialism is that lucifer hasn't yet been cast out of heaven.
Anyway. That's how I remember it. Haven't had that argument in nearly two decades.