mental soundness vs mental balance

mental soundness and mental balance both are nouns.

Word	Noun	Adjective	Verb	Adverb
mental soundness	Yes	No	No	No
mental balance	Yes	No	No	No

As nouns, mental soundness and mental balance are synonyms defined as:

mental soundness and mental balance: the healthy psychological state of someone with good judgment

mental soundness (noun)	mental balance (noun)
the healthy psychological state of someone with good judgment	the healthy psychological state of someone with good judgment