Since Adrien mentioned Marinette didn't like horror movies, it means he remembered what she told him when they were about to watch Solitude together back during Gorizilla. And that prompted me to compare the two episodes.
Here's a list of some similitudes and contrasts I have found.
Both episodes are centered around a movie. In Gorizilla, the events starts because Adrien wants to watch a particular movie featuring his deceased mother and he was unable to tell his father about it. Whereas in Vampigami, the events start because Adrien's grandparents wants to share a family moment with him and offer him tickets to a movie that means a lot to them and they are hoping it could mean a lot to Adrien and Marinette as well.
Additionally, we can highlight the contrast between Solitude and the Vampire Musical Horrific Show.
Solitude, as implied by André holding his script during Sole Crusher, is about how "It can be lonely when even your own family can't accept you for who you are". Whereas the Vampire Musical Horrific Show encouraged its audience to interact with the film and with each other to create a group experience. The movie in itself has a whole community attached to it.
The episode Gorizilla ended with Adrien watching his mother's movie at home alone with his father and it felt like a really solemn moment. While Vampigami ended with Adrien watching the movie at the theater with his grandparents and some friends while Marinette opt out because horror movies aren't her cup of tea.
Both episodes have two characters being mistaken for a couple. In Gorizilla, Adrien's fans think Marinette is his girlfriend. In Vampigami, Prem's complicity with Rose prompts Ray and his gang to insinuate he is in love with her.
Disguises are involved in both cases and movie projection is interrupted because of an akumatized.
Both have the villain tailing one of our heroes. In Gorizilla, Gabriel was suspecting Adrien to be Chat Noir while in Vampigami, Lila is trying to prove that Marinette is Ladybug.
Both episodes have a message about honesty and trust. But notice the difference in tone.
Gabriel (in Gorizilla) : All you had to do was ask me. [...] You should've trusted me, son. It's important for you and I to be able to trust each other. If you were to begin hiding the truth from me, then I'd naturally start imagining all kinds of things.
Adrien (in Vampigami) : Marinette, the only thing that could disappointed me is if you can't be honest with me and force yourself to do things that you don't want to only to please me.
In Gorizilla, there is a notion of monitoring Adrien's actions all the time (be it through his bodyguard or Adrien's fans publishing his whereabouts of social medias).
In Vampigami, Ladybug realizes the new Butterfly Holder is spying on them.
And that's about what I have noticed. Let me know if you have spot other parallels :)
