semifinalist vs competition

semifinalist and competition both are nouns.

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

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

semifinalist: one of four competitors remaining in a tournament by elimination
competition: the contestant you hope to defeat

Other hypernyms of semifinalist include challenger, competitor, contender, rival.

semifinalist (noun)	competition (noun)
one of four competitors remaining in a tournament by elimination	the act of competing as for profit or a prize
	an occasion on which a winner is selected from among two or more contestants
	the contestant you hope to defeat
	a business relation in which two parties compete to gain customers