lobefin vs coelacanth

lobefin and coelacanth both are nouns.

Word	Noun	Adjective	Verb	Adverb
lobefin	Yes	No	No	No
coelacanth	Yes	No	No	No

As nouns, coelacanth is a hyponym of lobefin; that is, coelacanth is a word with a more specific, narrower meaning than lobefin:

lobefin: any fish of the order Crossopterygii; most known only in fossil form
coelacanth: fish thought to have been extinct since the Cretaceous period but found in 1938 off the coast of Africa

Other hyponyms of lobefin include Latimeria chalumnae.

lobefin (noun)	coelacanth (noun)
any fish of the order Crossopterygii; most known only in fossil form	fish thought to have been extinct since the Cretaceous period but found in 1938 off the coast of Africa