I think that "Christmas Calendar" is a bit of a misnomer. To be precise, this is a variation on the tradition of the "Advent Calendar". Advent is the time of preparation for Christmas. Clearly the authors of the Calendar understand this, based on the graphic under day "1" :)
Edit: on second thought, i guess you've meant "Machine Learning Christmas" Calendar. That's fine. It just bothers me a bit that in the US people forget about Advent.
In Norwegian we use the terms "Christmas calendar" and "Advent calendar" (translated directly) interchangeably. This i probably why some of the calendars (under the https://bekk.christmas umbrella) are using the term incorrectly
I don't really think the difference is really notable. I knew it would be a daily calendar counting until Christmas. I guess I fall into the camp of not being a prescriptivist of language.
Looking forward to more posts. Hoping for a post about GANs!