winter break vs vacation

winter break and vacation both are nouns.

Word	Noun	Adjective	Verb	Adverb
winter break	Yes	No	No	No
vacation	Yes	No	Yes	No

As nouns, vacation is a hypernym of winter break; that is, vacation is a word with a broader meaning than winter break:

winter break: A school holiday in winter, the date and duration of which depends on the country.
vacation: leisure time away from work devoted to rest or pleasure

Other hypernyms of winter break include holiday.

winter break (noun)	vacation (noun)
A school holiday in winter, the date and duration of which depends on the country.	the act of making something legally void
	leisure time away from work devoted to rest or pleasure

winter break (verb)	vacation (verb)
	spend or take a vacation