billfish vs teleost

billfish and teleost both are nouns.

Word	Noun	Adjective	Verb	Adverb
billfish	Yes	No	No	No
teleost	Yes	No	No	No

As nouns, teleost is a hypernym of billfish; that is, teleost is a word with a broader meaning than billfish:

billfish: elongate European surface-dwelling predacious fishes with long toothed jaws; abundant in coastal waters
teleost: a bony fish of the subclass Teleostei

Other hypernyms of billfish include teleost fish, teleostan.

As nouns, teleost is a hypernym of billfish; that is, teleost is a word with a broader meaning than billfish:

Other hypernyms of billfish include teleost fish, teleostan.

billfish (noun)	teleost (noun)
giant warm-water game fish having a prolonged and rounded toothless upper jaw	a bony fish of the subclass Teleostei
elongate European surface-dwelling predacious fishes with long toothed jaws; abundant in coastal waters
primitive predaceous North American fish covered with hard scales and having long jaws with needlelike teeth
slender long-beaked fish of temperate Atlantic waters