thoughtfulness vs thoughtful

thoughtfulness is a noun but thoughtful is not a noun.

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

thoughtfulness (noun)	thoughtful (noun)
a considerate and thoughtful act
the trait of thinking carefully before acting
kind and considerate regard for others
a calm, lengthy, intent consideration

thoughtfulness (adjective)	thoughtful (adjective)
	exhibiting or characterized by careful thought
	taking heed; giving close and thoughtful attention
	considerate of the feelings or well-being of others
	having intellectual depth
	characterized by solemn, sincere manner