pith vs mental object

pith and mental object both are nouns.

Word	Noun	Adjective	Verb	Adverb
pith	Yes	No	Yes	No
mental object	Yes	No	No	No

As nouns, mental object is a hypernym of pith; that is, mental object is a word with a broader meaning than pith:

pith: the choicest or most essential or most vital part of some idea or experience
mental object: the sum or range of what has been perceived, discovered, or learned

Other hypernyms of pith include cognitive content, content.

pith (noun)	mental object (noun)
the choicest or most essential or most vital part of some idea or experience	the sum or range of what has been perceived, discovered, or learned
soft spongelike central cylinder of the stems of most flowering plants

pith (verb)	mental object (verb)
remove the pith from (a plant)