round robin vs tournament

round robin and tournament both are nouns.

Word	Noun	Adjective	Verb	Adverb
round robin	Yes	No	No	No
tournament	Yes	No	No	No

As nouns, tournament is a hypernym of round robin; that is, tournament is a word with a broader meaning than round robin:

round robin: a tournament in which every contestant plays every other contestant
tournament: a sporting competition in which contestants play a series of games to decide the winner

Other hypernyms of round robin include tourney.

round robin (noun)	tournament (noun)
a letter signed by a number of people	a sporting competition in which contestants play a series of games to decide the winner
a tournament in which every contestant plays every other contestant	a series of jousts between knights contesting for a prize