refusal vs subject matter

refusal and subject matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
refusal	Yes	No	No	No
subject matter	Yes	No	No	No

As nouns, subject matter is a hypernym of refusal; that is, subject matter is a word with a broader meaning than refusal:

Other hypernyms of refusal include content, message, substance.

refusal (noun)	subject matter (noun)
a message refusing to accept something that is offered	content communicating a message; what something is about
the act of refusing