protoctist vs protozoon

protoctist and protozoon both are nouns.

Word	Noun	Adjective	Verb	Adverb
protoctist	Yes	No	No	No
protozoon	Yes	No	No	No

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

protoctist: any of the unicellular protists
protozoon: any of diverse minute acellular or unicellular organisms usually nonphotosynthetic

Other hyponyms of protoctist include protozoan, alga, algae.

protoctist (noun)	protozoon (noun)
any of the unicellular protists	any of diverse minute acellular or unicellular organisms usually nonphotosynthetic