Hmm, in my opinion, Xeno (sex with aliens) and Anthro (sex with human like aliens) are very similar, but its more a mindset then anything else. I've read novels where a race of Aliens would qualify as anthro cats, anthro birds, etc, but it is xeno in my mind if the reason for the attraction is that they are aliens from another world, rather then that they are cat like, or bird like etc. So its basicly, what is the reason for you attraction, rather then the what your attracted to. But again, its all very vague and such.
I gotta say, I qualify as both, raguardless of how you define it.