Georgios Scholarios, Byzantine philosopher churchman and first Patriarch of Constantinople (= Gennadius II) after the Turkish conquest, criticized Origen for saying that "hellfire would not last forever" (quoted by Henry Chadwick, Early Christian Thought and the Classical Tradition, 2nd ed. 95).
Does Eastern Orthodoxy teach that those who do not end up in heaven go to a place of hellfire, and that this hellfire is without end? I often hear Greek Orthodox folk say other things.
Ευχαριστὠ!
As far as I can tell, there are indeed different teachings - or perhaps it is not truly so much differences as it is that things are expressed in different ways.
The Orthodox also allow space for saying they do not fully know the answers to some questions and do not tend to create explanations for things that are not known, but simply leave space for people to follow their conscience in some things, or consider others to be mysteries.
That said, I do most often hear that all humans have souls that will consciously experience the afterlife. Because God is everywhere, all will experience His Presence in some measure. For those who are aligned with His will, have sought to know Him, etc., His Presence will be experienced as love. For those who oppose Him, who hate Him, etc., His Presence will be unbearable - He is said in Scripture to be "a consuming fire". It is possible and reasonable that the overwhelming love, holiness, purity that is the essence of God's being could certainly be searing to those who hate it.
(This part is just myself speaking: there are Scriptures that speak of outer darkness, etc. and it makes sense to me that if there is a center place where the faithful will be, those who experience God as fire would try to escape. Of course being unable, but perhaps they can move further away, and probably would. My point is just that those kinds of passages can be consistent with the teaching.)
There is the hope that in God's mercy, perhaps this experience of God over time can purify these souls somehow, and perhaps they will all one day be reconciled to Him. However, we do not have that promise. It may not be so. Perhaps they will twist further and further away from God and be fully polluted. There is no Orthodox teaching on this. But many pray for the salvation of all. We can hope.
This is not all I hear. Some Orthodox speak of a fiery pit. Many (maybe most?) do speak of the final judgement and the probable impossibility of change after that. Many also speak of the impossibility of change after death, which would mean all is determined forever when we die.
I think that can be taken together to say there is some freedom given for a variety of interpretations.
I do not say all of this with any authority. But I have spoken with a number of priests, monastics, and laity, as well as read a number of articles on canonical Orthodox websites, and read some of the writings of the saints on this topic. That is the best overview I can give, based on that.