medicinal leech vs leech

medicinal leech and leech both are nouns.

Word	Noun	Adjective	Verb	Adverb
medicinal leech	Yes	No	No	No
leech	Yes	No	Yes	No

As nouns, leech is a hypernym of medicinal leech; that is, leech is a word with a broader meaning than medicinal leech:

medicinal leech: large European freshwater leech formerly used for bloodletting
leech: carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end

Other hypernyms of medicinal leech include bloodsucker, hirudinean.

medicinal leech (noun)	leech (noun)
large European freshwater leech formerly used for bloodletting	carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end
	a follower who hangs around a host (without benefit to the host) in hope of gain or advantage

medicinal leech (verb)	leech (verb)
	draw blood