tier vs rival

tier and rival both are nouns.

Word	Noun	Adjective	Verb	Adverb
tier	Yes	No	No	No
rival	Yes	Yes	Yes	No

As nouns, rival is a hypernym of tier; that is, rival is a word with a broader meaning than tier:

Other hypernyms of tier include challenger, competition, competitor, contender.

tier (noun)	rival (noun)
one of two or more layers one atop another	the contestant you hope to defeat
any one of two or more competitors who tie one another
a relative position or degree of value in a graded group
something that is used for tying
a worker who ties something

tier (adjective)	rival (adjective)
	as a rival in a competition

tier (verb)	rival (verb)
	be the rival of, be in competition with
	be equal to in quality or ability