fluke vs blood fluke

fluke and blood fluke both are nouns.

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

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

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

fluke (noun)	blood fluke (noun)
parasitic flatworms having external suckers for attaching to a host	flatworms parasitic in the blood vessels of mammals
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