solicitousness vs concern

solicitousness and concern both are nouns.

Word	Noun	Adjective	Verb	Adverb
solicitousness	Yes	No	No	No
concern	Yes	No	Yes	No

As nouns, concern is a hypernym of solicitousness; that is, concern is a word with a broader meaning than solicitousness:

solicitousness (noun)	concern (noun)
a feeling of excessive concern	something that interests you because it is important or affects you
	something or someone that causes anxiety; a source of unhappiness
	a feeling of sympathy for someone or something
	an anxious feeling
	a commercial or industrial enterprise and the people who constitute it

solicitousness (verb)	concern (verb)
	be relevant to
	be on the mind of