preconceived notion vs preconceived opinion

preconceived notion and preconceived opinion both are nouns.

Word	Noun	Adjective	Verb	Adverb
preconceived notion	Yes	No	No	No
preconceived opinion	Yes	No	No	No

As nouns, preconceived notion and preconceived opinion are synonyms defined as:

preconceived notion and preconceived opinion: an opinion formed beforehand without adequate evidence

Other synonyms of preconceived notion include parti pris, preconceived idea, preconception, prepossession.

preconceived notion (noun)	preconceived opinion (noun)
an opinion formed beforehand without adequate evidence	an opinion formed beforehand without adequate evidence