Alien deployment in TFTD and UFO work exactly the same way, there are Soldiers, Navigators, Medics, Technicians, Squad Leaders, Commanders, and 1 or 2 types of Terrorists (hence the 8 slots) but only 1 single race on a ufo.
Ethereal's don't have medics, engineers or navigators. I'm not sure why it is filled up with leaders tho, that might be wrong.