rag week vs week

rag week and week both are nouns.

Word	Noun	Adjective	Verb	Adverb
rag week	Yes	No	No	No
week	Yes	No	No	No

As nouns, week is a hypernym of rag week; that is, week is a word with a broader meaning than rag week:

rag week: a week at British universities during which side-shows and processions of floats are organized to raise money for charities
week: any period of seven consecutive days

Other hypernyms of rag week include hebdomad.

rag week (noun)	week (noun)
a week at British universities during which side-shows and processions of floats are organized to raise money for charities	any period of seven consecutive days
	hours or days of work in a calendar week
	a period of seven consecutive days (usually reckoned to be from Sunday to Saturday, or from Monday to Sunday)