trematode worm vs flatworm

trematode worm and flatworm both are nouns.

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

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

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

Other hypernyms of trematode worm include platyhelminth.

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