novillero vs bullfighter

novillero and bullfighter both are nouns.

Word	Noun	Adjective	Verb	Adverb
novillero	Yes	No	No	No
bullfighter	Yes	No	No	No

As nouns, bullfighter is a hypernym of novillero; that is, bullfighter is a word with a broader meaning than novillero:

novillero: a bullfighter who is required to fight bulls less than four years of age
bullfighter: someone who fights bulls

Other hypernyms of novillero include toreador.

novillero (noun)	bullfighter (noun)
a bullfighter who is required to fight bulls less than four years of age	someone who fights bulls