These are not all the same grains and don’t cook the same way. Farro can be used as a general term to describe all three. Farro and emmer are often used as common names for the same grain, Triticum dicoccum, also called farro medio. Spelt, Triticum spelta, is also called farro grande. Einkorn, Triticum monococcum, is also called farro piccolo. I think the farro recipes in Cooking are generally using emmer/faro medio/Triticum dicoccum.
