pith vs haecceity

pith and haecceity both are nouns.

Word	Noun	Adjective	Verb	Adverb
pith	Yes	No	Yes	No
haecceity	Yes	No	No	No

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

pith: the choicest or most essential or most vital part of some idea or experience
haecceity: the essence that makes something the kind of thing it is and makes it different from any other

Other hyponyms of pith include bare bones, hypostasis, quiddity, quintessence, stuff.

pith (noun)	haecceity (noun)
the choicest or most essential or most vital part of some idea or experience	the essence that makes something the kind of thing it is and makes it different from any other
soft spongelike central cylinder of the stems of most flowering plants

pith (verb)	haecceity (verb)
remove the pith from (a plant)