Annuki, Ennuki, Ennunki, are pretty much the same. Variations in spelling are significant in analyzing a word by systems like the Hebrew Kaballah, or Qabala, by which the individual letters have numerical values, and so the total value of any word (sumtotal of the numerical values of its constituent letters) represents a hidden meaning of that word which is consistant with all other words with the same numerical value. Analysis of the original Old Testament via this system gives one an esoteric angle on the story that is not implicit in the literal text.
So why, then, are the variations of the name Ennuki not important? First, because the vowels are not important. They may have been guides to pronunciation, but not much more. In Hebrew and in Arabic the letters A and E, Y and J are more or less interchangeable. Qabalistic practice is to subtract most or all of the vowels in a word to determine its numerical value. JHVH is Jehovah. Language is magic. The consonants are the engines, the vowels the exhaust.
Further, just as in English we pronounce each letter Ay, Bee, Cee, etc., the vowel following a consonant in Sumerian or Hebrew may simply indicate that letter's full pronunciation. In Sumer, N would be spoken as Nu; in Israel it would be Nun. In those days whole sentences may have been constructed of a single word, with each letter having its own meaning. If today we are more verbose, perhaps it is because we have more to hide.
We also have overlooked the equation, letter=number, which could potentially unite the arts with the sciences.
But the Gods and Goddesses await. And some are famished!
I posit that our local gods (not the names of alien races) began as qualities. As more and more spiritual energy was invested in these qualities, they accquired their own astral "chalice" to hold the prayers of their adherents. Thus JHWH, which represents a particular sequence of the four elements (fire, water, air and earth) became, via the successful application of the implicit formula, and the prayer energy of the Hebrews, their God Jehovah. Similarly, Shaitan, a fire entity of the south, the noonday desert sun, etc, entertained prayers from quite another group, cum sacrifices of humans, and became our modern Satan. This perspective makes it clear that we are wrong to blame the God for the behavior of his adherents; the God is simply the repository of their will.
It is humans who must answer for the excesses of the Gods whom they create and fortify.
Another mistake is to assume that Lucifer is another name for the Devil. In the Tarot of Crowley, The Devil is Baphomet, a horned androgynous being who symbolizes the blind will to procreate. Lucifer is a Latin word transliterated as "Light-bearer". Neither of these Gods equates with the Christian Devil.
Lucifer may be a later version of the Sumerian Enki, who in earlier posts here was described as the God who argued against turning humans into slaves. If you're into etymology, the similarity of the names Enki and Ennuki sticks out and calls for study. Some Sumerian Gods were absorbed into Egyptian culture. The Egyptian Goddess (finally we have a woman! But Elohim is the masculine plural of a feminine noun, and Jesus spoke the feminine singular Eloi, instead of invoking his "father" JHVH, when he was about to expire on the cross. But that's another rebus.) Nuit represents the sky, particularly at night when the stars are out. Nuit therefore may be construed to symbolize the reaches of space. Nuit, shortened to Nu, equals precisely the difference between "Enki" and "Ennuki". The latter are from space. The former was, but has dropped his loyalties to the aliens, and now sides with humans.
All this is a stretch on thin ice. I'm no linguist or expert on ancient civilizations. Just an agent trying to synthesize stuff. And I have not forgotten to define the Christian Devil. I just figured it's not my problem.