championship vs competition

championship and competition both are nouns.

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

As nouns, competition is a hypernym of championship; that is, competition is a word with a broader meaning than championship:

championship: a competition at which a champion is chosen
competition: an occasion on which a winner is selected from among two or more contestants

Other hypernyms of championship include contest.

championship (noun)	competition (noun)
the act of providing approval and support	the act of competing as for profit or a prize
a competition at which a champion is chosen	an occasion on which a winner is selected from among two or more contestants
the status of being a champion	the contestant you hope to defeat
	a business relation in which two parties compete to gain customers