senior vs dean

senior and dean both are nouns.

Word	Noun	Adjective	Verb	Adverb
senior	Yes	Yes	No	No
dean	Yes	No	No	No

As nouns, dean is a hyponym of senior; that is, dean is a word with a more specific, narrower meaning than senior:

Other hyponyms of senior include doyen, doyenne, senpai.

senior (noun)	dean (noun)
an undergraduate student during the year preceding graduation	an administrator in charge of a division of a university or college
a person who is older than you are	(Roman Catholic Church) the head of the College of Cardinals
	a man who is the senior member of a group

senior (adjective)	dean (adjective)
older; higher in rank; longer in length of tenure or service
used of the fourth and final year in United States high school or college
advanced in years; (`aged' is pronounced as two syllables)