Every season has something that makes them different from each other. In Season 1, the title of each episode appeared onscreen. In Season 2, Vampirina didn't cry. In Season 3, Edgar started to hang out with Vampirina more often because he finally found out that she and her family were vampires, and that monsters exist.
Vampirina's friend Bridget has a cat named Ms. Cuddlecakes, and in Take Your Pet to the Vet/Master and Commander (2015), there is also a cat with the same name at the vet. Both shows were created by Chris Nee.
Besides Vee herself, Poppy is the only character to appear in at least one segment of every single episode.
Chris Nee, the creator of the series, was not involved in season 3 due to leaving to work at Netflix. As such, story editor Chelsea Beyl took over as show runner.
Vampirina's fear of baby cows was mentioned in the episodes, Hiccupire and Bridget The Brave.