pensiveness vs thoughtfulness

pensiveness and thoughtfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
pensiveness	Yes	No	No	No
thoughtfulness	Yes	No	No	No

As nouns, thoughtfulness is a hypernym of pensiveness; that is, thoughtfulness is a word with a broader meaning than pensiveness:

pensiveness (noun)	thoughtfulness (noun)
deep serious thoughtfulness	a considerate and thoughtful act
persistent morbid meditation on a problem	the trait of thinking carefully before acting
	kind and considerate regard for others
	a calm, lengthy, intent consideration