respondent vs testee

respondent and testee both are nouns.

Word	Noun	Adjective	Verb	Adverb
respondent	Yes	Yes	No	No
testee	Yes	No	No	No

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

respondent: someone who responds
testee: someone who is tested (as by an intelligence test or an academic examination)

Other hyponyms of respondent include assenter, equivocator, hedger, tergiversator, interviewee, examinee.

respondent (noun)	testee (noun)
someone who responds	someone who is tested (as by an intelligence test or an academic examination)
the codefendant (especially in a divorce proceeding) who is accused of adultery with the corespondent

respondent (adjective)	testee (adjective)
replying