serious-mindedness vs earnestness

serious-mindedness and earnestness both are nouns.

Word	Noun	Adjective	Verb	Adverb
serious-mindedness	Yes	No	No	No
earnestness	Yes	No	No	No

As nouns, serious-mindedness and earnestness are synonyms defined as:

Other synonyms of serious-mindedness include seriousness, sincerity.

serious-mindedness (noun)	earnestness (noun)
the trait of being serious	the trait of being serious
	an earnest and sincere feeling