week from Monday vs week

week from Monday and week both are nouns.

Word	Noun	Adjective	Verb	Adverb
week from Monday	Yes	No	No	No
week	Yes	No	No	No

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

Other hypernyms of week from Monday include hebdomad.

week from Monday (noun)	week (noun)
a time period of a week or more	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)