thought vs mental object

thought and mental object both are nouns.

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

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

thought: the content of cognition; the main thing you are thinking about
mental object: the sum or range of what has been perceived, discovered, or learned

Other hypernyms of thought include cognitive content, content.

thought (noun)	mental object (noun)
the process of using your mind to consider something carefully	the sum or range of what has been perceived, discovered, or learned
the content of cognition; the main thing you are thinking about
the organized beliefs of a period or group or individual
a personal belief or judgment that is not founded on proof or certainty