concision vs pithiness

concision and pithiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
concision	Yes	No	No	No
pithiness	Yes	No	No	No

As nouns, concision and pithiness are synonyms defined as:

concision and pithiness: terseness and economy in writing and speaking achieved by expressing a great deal in just a few words

Other synonyms of concision include conciseness, succinctness.

concision (noun)	pithiness (noun)
terseness and economy in writing and speaking achieved by expressing a great deal in just a few words	terseness and economy in writing and speaking achieved by expressing a great deal in just a few words