While the likes of It's a Wonderful Life and 8-Bit Christmas are clear-cut Christmas movies, the debate rages on years after its release about whether Die Hard falls under that category. The term "Christmas adjacent" has been used to describe movies that take place during the holidays, but don't have any overt Christmas themes in their story. They're best exemplified by director Shane Black's films, which include the likes of Iron Man 3 and Kiss Kiss Bang Bang. Action is at the heart of the 1988 Bruce Willis film, and the story could have taken place at any time of the year with a few minor adjustments to dialogue and scenery. But it also contains sentimental themes closely associated with Christmas, which makes it something a little bit more than "Christmas adjacent." There's no better example of the difference than the first sequel, Die Hard 2: which was also set at Christmastime, but embodies completely different themes and ideas. Together, they prove that, just because a film is set at Christmas, it isn't automatically a Christmas movie.
Source：https://www.cbr.com/die-hard-is-a-christmas-movie-unlike-sequel/
