tactfulness vs courtesy

tactfulness and courtesy both are nouns.

Word	Noun	Adjective	Verb	Adverb
tactfulness	Yes	No	No	No
courtesy	Yes	No	No	No

As nouns, courtesy is a hypernym of tactfulness; that is, courtesy is a word with a broader meaning than tactfulness:

tactfulness: Behavior or actions characterized by careful consideration in dealing with others, to avoid giving offense.
courtesy: a courteous manner

Other hypernyms of tactfulness include tact, tactfulness, good manners.

tactfulness (noun)	courtesy (noun)
consideration in dealing with others and avoiding giving offense	a courteous or respectful or considerate act
Behavior or actions characterized by careful consideration in dealing with others, to avoid giving offense.	a courteous manner
	a courteous or respectful or considerate remark