Here's an example from Revelation 20:
13 And the sea gave up the dead which were in it, and death and Hades gave up the dead which were in them; and they were judged, every one of them according to their deeds.
14 Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire.
15 And if anyone's name was not found written in the book of life, he was thrown into the lake of fire.
-Gehenna is understood to be eternal hell. Hades is a temporary fiery place, and it says that at the end of the world, there will be no more need for Hades and death and hades will be thrown into Gehenna.
Hades to us, is purgatory but it's complicated.
This essay might help:
"This focuses upon the belief in sheol. I'm going to suggest that what the Latin word, "purgatorio" signifies, that is the place where we are purged of disordered self-love, the Hebrew word, "sheol" can also signify or denote. Just like the Greek word "hades" can denote it. Three words, perhaps with the same reality, with proper distinctions made, if we had the time and the energy and the know-how and so on. But I would suggest that "hades," the Greek word, is not normally associated with just simply "hell fire." "Gehenna" is the word that Jesus uses for hell fire, "where the worm dieth not" and there's this unquenchable fire. That's actually borrowed from the garbage dump outside of Jerusalem, "ge-hin-nom," the valley of hin-nom, which was where King Manasus sacrificed thousands of Israelite children to Molek, a demon god. After that nobody wanted to live in such defiled land, so it became the garbage dump, with fires continually burning. Nobody wanted to get near it because of defilement. It was a haunt of demons.
That was the image that Christ used for hell, as we normally associate it, but hades is a term that admits to a kind of double usage as we will see and as scholars have seen. For instance, Ellard Bailey in a book, "Death in the Literature of the Old Testament" speaks about how throughout the Old Testament, the belief is found that the good and the evil go down to sheol, it's the place where the righteous and the unrighteous go. In Brown, Driver and Briggs, one of the most authoritative reference works for understanding Hebrew words, you can look up sheol, and there you find that sheol is divided into two sections, one for the evil and one for the good.
You can actually find in the apocryphal work of 1st Enoch that it is divided up further into four sections: the evil section into two sections, those who are evil and those who are really evil; and also two sections for the good as well. R. L. Harris in another study speaks of sheol as the grave. He has been heavily criticized by scholars across the board for trying to reduce the word sheol down to being merely the grave. He especially ignored a major work in German that I came across by Afmar Kiel.
Now I know you're not just going to rush out to a seminary book store and purchase all of these works and read them by tomorrow morning, but you can get the tape or you can take notes on this and perhaps get some of these sources later on. Another scholar by the name of Hiedel spoke of sheol as existing in the Old Testament for the righteous. He also did a word study of the underworld, the nether world and saw it associated with the evil.
One of the key studies I came across, however, is by a man named Alexander, an Evangelical Protestant with decidedly non-Catholic leanings entitled, "The Old Testament View of Life After Death in Familias" in 1986, I believe. He rejects a lot of views that would basically make an Old Testament look like primitive garbage. He shows that sheol throughout the Old Testament represented the abode of the dead, the underworld for both the wicked and the righteous. For the wicked it was dark and silent and terrifying and a kind of imminent or ultimate preparation for final punishment. But for the good, there was hope, not pleasure, not comfort necessarily, but hope, great hope.
Now, working through these scholars and their studies of the Old Testament doctrine of sheol, I'd also done my own study. I came to the conclusion that they were right, that the Old Testament has a firm teaching that you could find in many different strata or levels of Old Testament tradition and there you find this belief that the soul goes on living somehow in a shadowy world where the righteous and the unrighteous have a share, although it's distinct; and it is not a pleasant place. It is not a pleasant place at all.........."
http://catholiceducation.org/articles/apologetics/ap0091.html