So this question came into my mind when I was watching Blood Ties (3 a.m. Eastern time on Lifetime!
In Forever Knight, Nick is the center of the story, and his struggle against his vampire nature is the driving force of the show's long-term story arc. In Blood Ties, on the other hand, the story is about a human, Vicki. Henry helps introduce her to the world of the paranormal, and the fact that he's a vampire lends a particular tone to the show, but the main story wouldn't change much if he were a different kind of supernatural creature.
But then again, you could say that about any story. When there are only so many basic plots and it's the details that make the stories different, it's not really fair to randomly swap out those details and claim you're keeping the essence of the story.
I haven't fully thought this through, but I wanted to open it up for discussion: what's the difference between a vampire story and a story with vampires in it, or is the difference even significant enough to be worth noting?