Codex Sinaiticus vs KJV?

realizing that they were neither written in English gives us a clue. These English renderings are interpretations from the original, attempting to maintain the integrity of the original, to the best ability of the interpreter or translator. Personally, I don't see the subtle differences in these as being noteworthy, as the meaning isn't modified. Some translations have differences which down right alter the meaning, and make it difficult to know which is accurate... and scholars go back and forth over it. The first one mentioned is the only one which is slightly noteworthy, in my opinion, because being kings vs. being a kingdom are different. But the add in of "the beginning/end" after alpha and omega, simply reinforces and defines what alpha and omega means. The which vs. who I don't read much into. Aside from the kings and kingdom part, I think its just a matter of poetic license, and doesn't affect meaning. just my opinion.