[count-your-change]

Both “sheol” and its Greek equivalent, ‘hades”, are used to describe what we in English would call “the grave”, the general grave of the dead without regard to their merits.

Tartarus was used only of the those demons in an condition of darkness and appears not to be a location but a condition.

Abaddon or avaddohn is simply Hebrew for destruction and was transliterated in the NT.

Gehenna was the “second death” of Revelation, named after the Vally of Hinnom where only those criminals thought so foul that they would not be “remembered” in a memorial tomb.

But unfortunately, translators have been inconsistent and have translated these terms chiefly as the English “hell” which in its original sense, only meant to conceal or hide in the earth.
No end of confusion has been the result.

“General knowledge of Greek and their reference to the underworld helps in the understanding.”

You're quite right!

[AnAmericanMother]

It’s the Limbo of the Fathers, and those are indeed demons, working the suburbs of Hell.