Originally Posted by
Kimmay
According to SE's own Encyclopedia Eorzea:
"In answer to the demands of their new positions, Nymian mages learned to bind and control faeries that they might entrust the otherworldly creatures with a share of the restorative duties."
"With soul crystals providing an anchor for their existence, these otherworldly servants are made manifest ..."
meaning that we are pulling the faeries from some other place, and they exist on their own. Whereas egis:
"'Egi' is the name given to the conjured avatars of a summoner. Only a practitioner whose aether has been stained by the essence of a primal can thenceforth shape her own energies into a willful embodiment of the original entity's dominant aspect."
An egi, like a carbuncle, is not some being called forth from another world, but our own aether given a shape of our choosing. Which is why /egiglamour exists within lore.