roundworm vs threadworm

roundworm and threadworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
roundworm	Yes	No	No	No
threadworm	Yes	No	No	No

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

roundworm: unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic
threadworm: small threadlike worm infesting human intestines and rectum especially in children

roundworm (noun)	threadworm (noun)
unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic	small threadlike worm infesting human intestines and rectum especially in children
infections of the skin or nails caused by fungi and appearing as itching circular patches