fluke vs liver fluke

fluke and liver fluke both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluke	Yes	No	No	No
liver fluke	Yes	No	No	No

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

fluke: parasitic flatworms having external suckers for attaching to a host
liver fluke: flatworm parasitic in liver and bile ducts of domestic animals and humans

Other hyponyms of fluke include Fasciola hepatica, Fasciolopsis buski, blood fluke, schistosome.

fluke (noun)	liver fluke (noun)
parasitic flatworms having external suckers for attaching to a host	flatworm parasitic in liver and bile ducts of domestic animals and humans
either of the two lobes of the tail of a cetacean
flat bladelike projection on the arm of an anchor
a barb on a harpoon or arrow
a stroke of luck