disbelief vs mental object

disbelief and mental object both are nouns.

Word	Noun	Adjective	Verb	Adverb
disbelief	Yes	No	No	No
mental object	Yes	No	No	No

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

disbelief: a rejection of belief
mental object: the sum or range of what has been perceived, discovered, or learned

Other hypernyms of disbelief include cognitive content, content.

disbelief (noun)	mental object (noun)
doubt about the truth of something	the sum or range of what has been perceived, discovered, or learned
a rejection of belief