My grandmother's maternal family (the Tsakgalou's) were greeks living in Constantinople at the time of the genocide and apparently my great-great grandparents were killed. Family lore has told that my great-grandparents died during some incident involving a train.
The Greek and Armenian genocides are very similar. The Greek Genocide was specifically a genocide of to Pontic and Anatolian Greek cultures and people however, not the Greeks as a whole, whereas the Armenian Genocide effected the entire Armenian nation. I personally believe this is why the Greek Genocide isn't spoken of as much as the Armenian Genocide.
Trains were used for both. I found some pics of the Greek Genocide, one contains a train