There are many different kinds of meditation or prayer, Christian and non-Christian. However, I am confused regarding actual difference because these varieties, both Christian and non-Christian, seem largely to be arbitrarily constructed.
This question asks specifically about the rosary vs a mantra while I am interested in all methods generally. This one asks about sharing Bible references on the correct way to meditate but I think falls short as I do not believe the Bible is a meditation textbook. I also think none of the answers address my question as they seem to straw-man eastern meditation as harmful, demonic, or dulling.
That said, what do the Orthodox consider to be the characteristics that distinguish (for example) hesychasm from Patriarch zen? The practitioner of Patriarch zen assumes a still posture and remains attentive while removing all thoughts or images from her mind.
On the other hand, Wikipedia says (regarding hesychasm):
... that the primary task of the Hesychast is to engage in mental ascesis. This mental ascesis is the rejection of tempting thoughts (the "thieves") that come to the Hesychast as he watches in sober attention in his hermitage.
Sober, attentive watching. Is there a clear, defining line between meditations that are acceptable for Orthodox Christians and those that aren't? If so, what is it? If I don't yet have the opportunity to learn from a starets (please forgive me if that is the incorrect term), should I learn Patriarch zen from a righteous man who believes it will lead Christians toward God?
As far as I can tell, the answer is yes because it is the intention, correctness of practice, and unending goodness of our Lord that determines results. However, I would much rather admit my own fault than attempt to outsmart two-thousand years of great saints. Answers should reference official statements from authority figures in the Orthodox church. Thank you very much!