What does the Orthodox church consider to be the defining features of Christian meditation? 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!
I'm a Catholic, so I guess you can take my words with a grain of salt, but I think the defining feature of Christian meditation is the focus on God through Grace.
From my point of view, the physical techniques that the, say, Buddhists use are not wrong per se, but rather are just things humans can do to help them contemplate something. Since Buddhists and Christians are both humans, to focus their minds, regardless on what each is focusing on, would reasonably involve similar techniques. It's not as if a Buddhist's body works differently than a Christian's!
What becomes important then is what that something we are contemplating is. We Christians contemplate God, and Buddhist contemplate &quot;nothing&quot;*. Ultimately, we can only contemplate God by Grace, so Buddhists might get something like a glimpse, but they can't truly experience the &quot;uncreated Light.&quot;
Here's some of Dr. David Bentley Hart's (an Orthodox Christian: pray for him. He's have serious health problems right now) thoughts on Zen Buddhism:

Every contemplative tradition necessarily stresses the need to discipline desire, to control the powers of both body and mind, to cultivate dispossession of the self, to learn detachment from finite things, to sacrifice discrete concepts about the truth for the sake of an immediate experience of the truth, and so forth.
Of greater interest to the Western reader, I would claim, is the actual content of the experience toward which Dogen urges his readers. I think there is more than a verbal or affective similarity between some of Dogen’s formulations and, for instance, Traherne’s or Blake’s or Dostoyevsky’s descriptions of seeing eternity within time, or paradise within the world of suffering and death. It would be presumptuous and reckless simply to claim that, when Dogen speaks of seeing that luminous wisdom that precedes, fills, and transcends all existing things, he is speaking of, say, the eternal Logos of Christian belief. But I would certainly insist that he is bearing witness to a genuine glimpse of that reality, in a way both beautifully distinctive and eminently worthy of reverence.
Source: http://www.firstthings.com/article/2011/12/luminous-wisdom

Here's another article concerning Christian meditation vs Buddhism: http://www.antiochian.org/mindfulness-known-church-fathers
*It's not exactly &quot;nothing&quot; in the sense we Westerners use the word. Buddhists seem to contemplate in part how the reifications of our mind are not based in reality, and that reification is itself deceitful to our consciousness. No-reifications can also be called &quot;nothing&quot; or &quot;no-thing&quot; (&quot;rei&quot; is the Latin word that corresponds with the English word &quot;thing&quot;). By removing the reification fictions of our mind, Buddhists believe they can see reality as it really is. However, I'm willing to be corrected on this point by those with greater knowledge.
Christi pax.