This independent free-lance journalist has performed a very significant piece of investigation on a massacre of residents of a Syrian town (see this and this) that happened last year to back up his conclusions in this article. He starts out with the evidence which leads inexorably to the following conclusions:
... as the Kessab massacre demonstrates, the so-called "moderate" FSA [Free Syrian Army] is an integral and indistinguishable component of the proxy terrorist army that Ankara and its Washington ally are supporting to overthrow the elected government of President Assad. Any difference is patently just a figment of imaginative propaganda.
Obama, while at the Paris climate change summit this week (appropriately, a "hot-air" conference of world leaders), has this week reiterated calls on Russia to focus its military campaign on the Islamic State and to halt its aerial attacks on "moderate rebels".
The American president and his Turk ally are in no position to lecture anybody about "terrorists" and "moderates". They are all part of the same criminal gang, and that gang includes Obama and Erdogan.