semifinalist vs contender

semifinalist and contender both are nouns.

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

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

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

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

semifinalist (noun)	contender (noun)
one of four competitors remaining in a tournament by elimination	the contestant you hope to defeat