mental object vs cognitive content

mental object and cognitive content both are nouns.

Word	Noun	Adjective	Verb	Adverb
mental object	Yes	No	No	No
cognitive content	Yes	No	No	No

As nouns, mental object and cognitive content are synonyms defined as:

mental object and cognitive content: the sum or range of what has been perceived, discovered, or learned

Other synonyms of mental object include content.

mental object (noun)	cognitive content (noun)
the sum or range of what has been perceived, discovered, or learned	the sum or range of what has been perceived, discovered, or learned