common roundworm vs nematode

common roundworm and nematode both are nouns.

Word	Noun	Adjective	Verb	Adverb
common roundworm	Yes	No	No	No
nematode	Yes	No	No	No

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

common roundworm: intestinal parasite of humans and pigs
nematode: unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

Other hypernyms of common roundworm include nematode worm, roundworm.

common roundworm (noun)	nematode (noun)
intestinal parasite of humans and pigs	unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic