lamprey eel vs jawless fish

lamprey eel and jawless fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
lamprey eel	Yes	No	No	No
jawless fish	Yes	No	No	No

As nouns, jawless fish is a hypernym of lamprey eel; that is, jawless fish is a word with a broader meaning than lamprey eel:

lamprey eel: primitive eellike freshwater or anadromous cyclostome having round sucking mouth with a rasping tongue
jawless fish: eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms

Other hypernyms of lamprey eel include agnathan, jawless vertebrate.

lamprey eel (noun)	jawless fish (noun)
primitive eellike freshwater or anadromous cyclostome having round sucking mouth with a rasping tongue	eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms