ranking vs senior

ranking and senior both are nouns.

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

ranking (noun)	senior (noun)
position on a scale in relation to others in status or rank or achievement	an undergraduate student during the year preceding graduation
	a person who is older than you are

ranking (adjective)	senior (adjective)
having a higher rank	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)