If we were talking in Vampire: The Masquerade terms, Mick's Humanity score would be off the charts. Not seeing eye-to-eye on vampire stuff will actually remind Mick of home (for better or worse), as he and his best buddy (a 400+ years old vampire) bicker constantly about right and wrong, vampires vs. humans and so on and so forth.

Which isn't to say I expect Katherine to let Mick in on her own self being a vampire. But still, I can see heated debates. :D

Since Moonlight vamps are so different from other canons, I think it's safe to say neither type vamp will recognize the other as such. Y/N/cookies?