holiday vs winter break

holiday and winter break both are nouns.

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

As nouns, winter break is a hyponym of holiday; that is, winter break is a word with a more specific, narrower meaning than holiday:

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

Other hyponyms of holiday include half-term, vac, vacay, field day, outing, picnic, honeymoon, paid vacation.

holiday (noun)	winter break (noun)
leisure time away from work devoted to rest or pleasure	A school holiday in winter, the date and duration of which depends on the country.
a day on which work is suspended by law or custom

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