evasion vs quiddity

evasion and quiddity both are nouns.

Word	Noun	Adjective	Verb	Adverb
evasion	Yes	No	No	No
quiddity	Yes	No	No	No

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

evasion: a statement that is not literally false but that cleverly avoids an unpleasant truth
quiddity: an evasion of the point of an argument by raising irrelevant distinctions or objections

Other hyponyms of evasion include circumlocution, indirect expression, doublespeak, hedge, hedging, cavil, quibble.

evasion (noun)	quiddity (noun)
the act of physically escaping from something (an opponent or a pursuer or an unpleasant situation) by some adroit maneuver	the essence that makes something the kind of thing it is and makes it different from any other
nonperformance of something distasteful (as by deceit or trickery) that you are supposed to do	an evasion of the point of an argument by raising irrelevant distinctions or objections
the deliberate act of failing to pay money
a statement that is not literally false but that cleverly avoids an unpleasant truth