I'm only on this board right now because I can't sleep, so I'm not going to write a treatise. But "hell" is a Germanic-based word and it seems to be used to cover anything identified with those who have died in their sins... the grave, the holding place, the prison, underworld torment. I know people are going to continue to use it generically like this, but all these scriptural identifications cannot be the same thing, and thus one word can mislead.
But even what little has already been discussed seriously in this thread can overlap in ways not possible. For example, if hell is separation from God, that eliminates the Old Testament word anglicised as "sheol" because passages (Psalm 139 and others) say God is there. As for the New Testament "hades," as in Luke 16, it's interesting to note that, while Jesus tells the story of the rich man and Lazarus, there is conversation between the 'dead' rich man and Abraham [that Abe was a true patriarch is the reason I cannot accept that this is just a parable]. God does not enter the exchange, and the poor man, Lazarus, seems to be comforted by being in the presence of Abraham (not God; though we don't presume that's the case, it's just not in bounds of the story). So God, in the story, doesn't talk to the rich man, but he doesn't talk to Abe and Laz either. We must assume he does have pesence that place, and it doesn't seem reasonable that people on the 'good side' can intersect the 'bad side' but God himself can not or would not. Or, maybe, that's why He doesn't appear at all this story, except in Jesus who tells it.
The the "lake of fire," into which hell [hades] is thrown would then seem to be the only place of complete separation from God, if such exists. An extrabiblical assumption I've heard is that the l.o.f. is "hell's hell;" of what "hell" already is, in terms of a place of torment, the l.o.f. torments hell in the same way... comparable to how the destructive force of an atomic [fission] bomb is only a 'trigger' to a hydrogen [fussion] bomb, which is then thousands of times more force.
So, I don't really know, and perhaps scripture is not so definitive as we may wish because we are not meant to. But it's plain enough "hell"-- sheol, gehenna, hades, the lake of fire, or any other place for the unrepentant, is to be avoided at all costs. And since we can't pay "all costs" we should be thankful and repentant each day that Someone who could did.