I don’t think our understandings are really all that different. On paper, very different. But in substance, I don’t think so.
If I’m not mistaken, the Orthodox do not believe in a “physical place” called Purgatory. Catholics don’t really either… Purgatory is the stage in the salvation process where were a cleansed of our sins via fire.
Catholic theologians often theorize regarding how long this process can take and that prayer for the dead can help potentially speed up someone’s time in the purging process (aka Purgatory). Some Catholic theologians even theorize where this process might take place. However, for the most part, Orthodox Theologians and faithful don’t think about it. They consider it a mystery and don’t focus on trying to theorize how it works.
Personally, I haven’t read anything regarding this process from the Orthodox Christians which contradicts what Catholics know and theorize about Purgatory.
I hope what I just wrote makes sense. God Bless.