Well, quick question, long answer: The truth is that if it looks a lot, but what I have done is to draw it by hand, fix it with Photoshop, and leave it "nice".
Possibly it looks like some of those images, because I base myself on them ... and I try to make it as similar as possible to the original. And if it gives rise to confusion as it seems, you may have achieved what you wanted, which is that it resembles the images you take as a reference.
That and that is a skull ... and this almost always has the same shape. I hope I have clarified your doubts.
I understand your point but all im saying is we have had a really big discussion about people tracing over images, not saying your doing it here but in the future just strive away from doing that so nothing comes back on you, references are fine to use but tracing over them or whatever the case may be isn't good. Also, the dark side of the skull, make that a little less dark and do more highlights around the face area. The blue areas could use some highlights also as in the first main image.