Gender Non Conformity is a way for those of us who aren't entirely masculine or feminine to also be normal people. Its not a way to be uniquely identified because of some label. Its a way to be included into society as we are bringing our unique flavor of humanity to the table as also "normative."
It solves the problem of being just fine with your genitalia and body assignment but also recognizing that you may have traits of the opposite sex and that they should be embraced and not hidden or repressed. That the boxes of Male or Female do not represent you as you are. That you are some combination a third gender or fourth or on some sort of sliding scale.
Of course there are nuanced differences in some other definitions. But, here is a simple one, hope it helps!