agnosticism vs disbelief

agnosticism and disbelief both are nouns.

Word	Noun	Adjective	Verb	Adverb
agnosticism	Yes	No	No	No
disbelief	Yes	No	No	No

As nouns, disbelief is a hypernym of agnosticism; that is, disbelief is a word with a broader meaning than agnosticism:

Other hypernyms of agnosticism include unbelief.

agnosticism (noun)	disbelief (noun)
the disbelief in any claims of ultimate knowledge	doubt about the truth of something
a religious orientation of doubt; a denial of ultimate knowledge of the existence of God	a rejection of belief