I don't think all motivations of the same, no. I do think they are all underpinned by sexism, though. Veering into outright misogyny.
Whatever reason a man has for wanting to be thought of as female, it's using their internal concept of womanhood as a means to do it.
You have to view women as a tool for your own needs, in order to do that. A resource to be utilised on your own behalf.
So, to me, there is very little difference between a man who wants to use a woman for reason A or motive B. (Or C, D, E and F for that matter!)