week vs calendar week

week and calendar week both are nouns.

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

As nouns, week and calendar week are synonyms defined as:

week and calendar week: a period of seven consecutive days (usually reckoned to be from Sunday to Saturday, or from Monday to Sunday)

week (noun)	calendar week (noun)
any period of seven consecutive days	a period of seven consecutive days (usually reckoned to be from Sunday to Saturday, or from Monday to Sunday)
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)