Die Hard is a Christmas Movie: Set at a Christmas party. Christmas themes (Protagonist trying to reconcile with his wife and kids for the holidays, seems like the Christmas spirit to me). Christmas music. Side character redemption arc. Several mentions of Christmas characters and items. Ho Ho Ho now I have a machine gun.
Die Hard 2 is NOT a Christmas movie. Simply an airport action movie set at Christmas time. No Christmas themes (he and his wife flying separately to see her family?), other than a joke about stealing presents and one about Santa flying by, no Christmasy stuff thrown about. This is one that, as others mentioned above, could be happening anytime.
Lethal Weapon is in the same category as Die Hard 2.