trematode vs flatworm

trematode and flatworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
trematode	Yes	No	No	No
flatworm	Yes	No	No	No

As nouns, flatworm is a hypernym of trematode; that is, flatworm is a word with a broader meaning than trematode:

trematode: parasitic flatworms having external suckers for attaching to a host
flatworm: parasitic or free-living worms having a flattened body

Other hypernyms of trematode include platyhelminth.

trematode (noun)	flatworm (noun)
parasitic flatworms having external suckers for attaching to a host	parasitic or free-living worms having a flattened body