protoctist vs protozoan

protoctist and protozoan both are nouns.

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

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

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

Other hyponyms of protoctist include protozoon, alga, algae.

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

protoctist (adjective)	protozoan (adjective)
	of or relating to the Protozoa