wheat eelworm vs nematode

wheat eelworm and nematode both are nouns.

Word	Noun	Adjective	Verb	Adverb
wheat eelworm	Yes	No	No	No
nematode	Yes	No	No	No

As nouns, nematode is a hypernym of wheat eelworm; that is, nematode is a word with a broader meaning than wheat eelworm:

wheat eelworm: small roundworm parasitic on wheat
nematode: unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

Other hypernyms of wheat eelworm include nematode worm, roundworm.

wheat eelworm (noun)	nematode (noun)
small roundworm parasitic on wheat	unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic