soberness vs serious-mindedness

soberness and serious-mindedness both are nouns.

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

As nouns, serious-mindedness is a hypernym of soberness; that is, serious-mindedness is a word with a broader meaning than soberness:

Other hypernyms of soberness include earnestness, seriousness, sincerity.

soberness (noun)	serious-mindedness (noun)
a manner that is serious and solemn	the trait of being serious
the state of being sober and not intoxicated by alcohol