competition vs tier

competition and tier both are nouns.

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

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

competition (noun)	tier (noun)
the act of competing as for profit or a prize	one of two or more layers one atop another
an occasion on which a winner is selected from among two or more contestants	any one of two or more competitors who tie one another
the contestant you hope to defeat	a relative position or degree of value in a graded group
a business relation in which two parties compete to gain customers	something that is used for tying
	a worker who ties something