I work in a public school. As a result, I've occasionally been corrected - very gently, I must say - when I refer to the 2 week vacation at the end of the year as "Christmas Break".
Oh, no, I am informed, it's a GENERIC holiday celebration (I generally refrain from pointing out that HOLIDAY is a variant of the original HOLY DAY). Just happens that SO many important holidays occur around this time that it's convenient to adjourn for vacation.
I always respond by saying, "I'll call it Winter Break the very first year that it DOESN'T include Christmas".
Christmas is the ONLY reason for the break