Classification of Spirits
Herein is a brief and concise exposé of the principal differences between Angels, Elementals, and Demons.
Angels
Angels, though themselves divided into numerous orders and classes, possess generally the following characteristics:
They are entirely benevolent in nature and operation, the conscient administrators of the Divine Will upon the plane of the material universe; that they are responsible, not irresponsible agents, and therefore capable of fall; and that they are independent of the currents of the infinite Secret Forces of Nature, and can therefore act beyond them, though their classification and qualities will cause them to be more sympathetic with certain among these forces than with the rest, and this in varying degree. Also that they are superior in power to Men, Spirits, Elementals, and Devils.
Elementals
The Elementals on the other hand, though consisting of an infinitude of classes, are the Forces of the Elements of Nature, the administrators of the currents thereof; and can therefore never act beyond and independently of their own particular currents. In a sense, therefore, they are irresponsible for the action of a current as a whole, though responsible for the part thereof in which they immediately act. Therefore also they are at the same time subject to the general current of the Force, wherein they live, move, and have their being; though superior to the immediate and particular part of it which they direct. Such races, superior to man in intuition, and magical powers; inferior to him in other ways; superior to him in their power in a particular current of an Element; inferior to him in only partaking of the nature of that one Element; are of necessity to be found constantly recurring in all the Mythologies of Antiquity. The Dwarfs and Elves of the Scandinavians; the Nymphs, Hamadryads, and Nature Spirits of the Greeks; the Fairies good and bad of the legends dear to our childish days the host of Mermaids, Satyrs, Fauns, Sylphs, and Fays; the Forces intended to be attracted and propitiated by the Fetishes of the Negro-Race; are for the most part no other thing than the ill-understood manifestations of this great class, the Elementals. Among these, some, as I have before observed, are good; such are the Salamanders, Undines, Sylphs, and Gnomes, of the Rosicrucian Philosophy; many are frightfully malignant, delighting in every kind of evil, and might easily be mistaken for Devils by the uninitiated, save that their power is less; a great proportion are neither good nor evil, irrationally working either; just as a monkey or a parrot might act; in fact such closely resemble animals in their nature, and especially combinations of animals, in which forms distorted and mingled, would lie their symbolic manifestation. Another very large class, would not act irrationally in this manner; but with intent, only always following the predominant force either good or evil in their then entourage; a spirit of this kind, for example, attracted into an assembly of good persons would endeavour to excite their ideas towards good; attracted among evil-minded persons would incite them mentally to crime. Among how many criminals is not their only excuse that they “thought they kept hearing something telling them to commit the crime”! Yet these suggestions would not always arise from Elementals alone, but frequently from the depraved astral remnants of deceased evil persons.
Demons
Devils, on the other hand, are far more powerful than Elementals, but their action for Evil is parallel to that of the Good Angels for Good; and their malignancy is far more terrible than that of the Evil Elementals, for not being, like them, subjected to the limits of a certain current, their sphere of operation extends over a far greater area; while the Evil they commit is never irrational or mechanical, but worked with full consciousness and intent.
Taken primarily from the Sacred Magic of Abremelin the Mage.