It really depends on who gets to decide. I say that both are holiday movies and I say the viewer decides for themselves if they are holiday movies or not. Bruce Willis stated that Die Hard is not a Christmas movie but I don't think it's up to him to decide. I say, leave it up to the opinion of the person watching the movies.

The real question is why anyone cares.

But the difference between them is in the body count between the 2 movies (and Alan Rickman, of course). The kid doesn't kill anyone to be reunited with his family and actually likes not having them around, which means this isn't actually about family togetherness which is the essence of modern Xmas (besides selling as much shit as possible). Die Hard showed the lengths a real family man will go through to not only be with his family during the holidays and work and compromise through family difficulties, but is also willing to kill a bunch of people who are in his way to do so - making this a true "spirit of Xmas" flick - with the bonus of them making new friends to share next Xmas with. Just ignore the bullet riddled corpse in the elevator.